Trial Outcomes & Findings for Sarilumab COVID-19 (NCT NCT04327388)

Last Updated: 2025-09-24

Results Overview

Time to improvement of greater than or equal (\>=) 2 points in clinical status assessment was defined as time (in days) from first dose of study drug to the time of first occurrence of improvement of \>=2 points in clinical status of participants assessed using 7-point ordinal scale (calculated as: Date of first occurrence/episode of the event - date of first dose + 1). Seven-point ordinal scale for clinical assessment ranges from 1= death; 2= hospitalized, on invasive mechanical ventilation/ECMO; 3= hospitalized, on non-invasive ventilation/high flow oxygen devices; 4= hospitalized, requiring supplemental oxygen; 5= hospitalized, not requiring supplemental oxygen - requiring ongoing medical care (COVID-19 related/otherwise); 6= hospitalized, not requiring supplemental oxygen - no longer required ongoing medical care; 7= not hospitalized, higher score = less severity. Kaplan-Meier method was used for analysis.

Recruitment status

COMPLETED

Study phase

PHASE3

Target enrollment

420 participants

Primary outcome timeframe

Baseline to Day 29

Results posted on

2025-09-24

Participant Flow

Study was conducted at 46 active centers in 11 countries. A total of 431 participants were screened between 28 March 2020 and 02 July 2020, of which 10 participants were screen failures and 1 participant was randomized twice and thus excluded. Therefore, a total of 420 participants were randomized in the study treatment by the interactive response technology (IRT) (2:2:1 ratio) to receive sarilumab 200 milligrams (mg)/400 mg and placebo. Screen failures were mainly due to exclusion criteria met.

Randomization was stratified by severity of illness (severe disease, critical disease) and use of systemic corticosteroids (Yes/No).

Participant milestones

Participant milestones
Measure	Sarilumab 200 mg Sarilumab 200 mg, single dose of intravenous (IV) injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in fraction of inspired oxygen (FiO2) requirement or * Required vasopressors, extracorporeal membrane oxygenation (ECMO) or development of multi-organ dysfunction.	Sarilumab 400 mg Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Overall Study STARTED	161	173	86
Overall Study Treated	159	173	84
Overall Study Participants Who Received Second Dose	13	11	5
Overall Study COMPLETED	141	153	75
Overall Study NOT COMPLETED	20	20	11

Reasons for withdrawal

Reasons for withdrawal
Measure	Sarilumab 200 mg Sarilumab 200 mg, single dose of intravenous (IV) injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in fraction of inspired oxygen (FiO2) requirement or * Required vasopressors, extracorporeal membrane oxygenation (ECMO) or development of multi-organ dysfunction.	Sarilumab 400 mg Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Overall Study Adverse Event	17	18	9
Overall Study Other	1	2	0
Overall Study Randomized and not treated	2	0	2

Baseline Characteristics

Sarilumab COVID-19

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Sarilumab 200 mg n=161 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=86 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Total n=420 Participants Total of all reporting groups
Age, Continuous	58.3 years STANDARD_DEVIATION 13.7 • n=5 Participants	58.0 years STANDARD_DEVIATION 14.1 • n=7 Participants	59.9 years STANDARD_DEVIATION 14.8 • n=5 Participants	58.5 years STANDARD_DEVIATION 14.1 • n=4 Participants
Sex: Female, Male Female	52 Participants n=5 Participants	74 Participants n=7 Participants	30 Participants n=5 Participants	156 Participants n=4 Participants
Sex: Female, Male Male	109 Participants n=5 Participants	99 Participants n=7 Participants	56 Participants n=5 Participants	264 Participants n=4 Participants
Race (NIH/OMB) American Indian or Alaska Native	2 Participants n=5 Participants	2 Participants n=7 Participants	1 Participants n=5 Participants	5 Participants n=4 Participants
Race (NIH/OMB) Asian	5 Participants n=5 Participants	9 Participants n=7 Participants	6 Participants n=5 Participants	20 Participants n=4 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants	1 Participants n=4 Participants
Race (NIH/OMB) Black or African American	3 Participants n=5 Participants	5 Participants n=7 Participants	1 Participants n=5 Participants	9 Participants n=4 Participants
Race (NIH/OMB) White	128 Participants n=5 Participants	128 Participants n=7 Participants	69 Participants n=5 Participants	325 Participants n=4 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants	3 Participants n=7 Participants	0 Participants n=5 Participants	3 Participants n=4 Participants
Race (NIH/OMB) Unknown or Not Reported	23 Participants n=5 Participants	26 Participants n=7 Participants	8 Participants n=5 Participants	57 Participants n=4 Participants
Clinical Status: 7-point ordinal scale Scale Score 1	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Clinical Status: 7-point ordinal scale Scale Score 2	17 Participants n=5 Participants	24 Participants n=7 Participants	10 Participants n=5 Participants	51 Participants n=4 Participants
Clinical Status: 7-point ordinal scale Scale Score 3	28 Participants n=5 Participants	21 Participants n=7 Participants	11 Participants n=5 Participants	60 Participants n=4 Participants
Clinical Status: 7-point ordinal scale Scale Score 4	113 Participants n=5 Participants	128 Participants n=7 Participants	65 Participants n=5 Participants	306 Participants n=4 Participants
Clinical Status: 7-point ordinal scale Scale Score 5	3 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	3 Participants n=4 Participants
Clinical Status: 7-point ordinal scale Scale Score 6	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Clinical Status: 7-point ordinal scale Scale Score 7	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants

PRIMARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on modified intention-to-treat (mITT) population which included all participants who were treated with study medication and were analyzed according to the initial treatment assigned to the participant (as randomized).

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Time to Improvement in Clinical Status of Participants (Using 7-point Ordinal Scale Score) by at Least 2 Points	10.0 days Interval 9.0 to 12.0	10.0 days Interval 9.0 to 13.0	12.0 days Interval 9.0 to 15.0

SECONDARY outcome

Timeframe: Day 29

Population: Analysis was performed on mITT population.

Percentage of participants who were alive at Day 29 were reported in this outcome measure.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Participants Who Were Alive at Day 29	89.9 percentage of participants	91.9 percentage of participants	91.7 percentage of participants

SECONDARY outcome

Timeframe: Baseline, Days 4, 7, 15, 21, and 29

Population: Analysis was performed on mITT population.

Clinical status of participants was assessed using 7-point ordinal scale ranges from: 1= death; 2= hospitalized, on invasive mechanical ventilation/ECMO; 3= hospitalized, on non-invasive ventilation/high flow oxygen devices; 4= hospitalized, requiring supplemental oxygen; 5= hospitalized, not requiring supplemental oxygen - requiring ongoing medical care (COVID-19 related/otherwise); 6= hospitalized, not requiring supplemental oxygen - no longer required ongoing medical care; 7= not hospitalized, higher score=less severity. Percentage of participants With \>=1 point improvement in clinical status from Baseline at Days 4, 7, 15, 21, and 29 (assessed using the 7-point ordinal scale) were reported.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Participants With Improvement in Clinical Status (According to 7-point Ordinal Scale Score) by at Least 1 Point From Baseline at Days 4, 7, 15, 21, and 29 Day 4	25.2 percentage of participants	25.4 percentage of participants	23.8 percentage of participants
Percentage of Participants With Improvement in Clinical Status (According to 7-point Ordinal Scale Score) by at Least 1 Point From Baseline at Days 4, 7, 15, 21, and 29 Day 7	51.6 percentage of participants	48.6 percentage of participants	42.9 percentage of participants
Percentage of Participants With Improvement in Clinical Status (According to 7-point Ordinal Scale Score) by at Least 1 Point From Baseline at Days 4, 7, 15, 21, and 29 Day 15	74.8 percentage of participants	76.9 percentage of participants	71.4 percentage of participants
Percentage of Participants With Improvement in Clinical Status (According to 7-point Ordinal Scale Score) by at Least 1 Point From Baseline at Days 4, 7, 15, 21, and 29 Day 21	80.5 percentage of participants	81.5 percentage of participants	85.7 percentage of participants
Percentage of Participants With Improvement in Clinical Status (According to 7-point Ordinal Scale Score) by at Least 1 Point From Baseline at Days 4, 7, 15, 21, and 29 Day 29	84.9 percentage of participants	84.4 percentage of participants	88.1 percentage of participants

SECONDARY outcome

Timeframe: Baseline, Days 4, 7, 15, 21, and 29

Population: Analysis was performed on mITT population. Here, 'number analyzed' = participants with available data for each specified category.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Change From Baseline at Days 4, 7, 15, 21, 29 in 7-point Ordinal Scale Score Day 4	0.1 scores on a scale Standard Deviation 0.9	0.1 scores on a scale Standard Deviation 1.0	0.2 scores on a scale Standard Deviation 0.9
Change From Baseline at Days 4, 7, 15, 21, 29 in 7-point Ordinal Scale Score Day 7	0.7 scores on a scale Standard Deviation 1.5	0.7 scores on a scale Standard Deviation 1.6	0.7 scores on a scale Standard Deviation 1.4
Change From Baseline at Days 4, 7, 15, 21, 29 in 7-point Ordinal Scale Score Day 15	1.9 scores on a scale Standard Deviation 1.8	2.0 scores on a scale Standard Deviation 1.9	1.7 scores on a scale Standard Deviation 1.8
Change From Baseline at Days 4, 7, 15, 21, 29 in 7-point Ordinal Scale Score Day 21	2.3 scores on a scale Standard Deviation 1.9	2.3 scores on a scale Standard Deviation 1.9	2.5 scores on a scale Standard Deviation 1.7
Change From Baseline at Days 4, 7, 15, 21, 29 in 7-point Ordinal Scale Score Day 29	2.5 scores on a scale Standard Deviation 1.9	2.5 scores on a scale Standard Deviation 1.9	2.7 scores on a scale Standard Deviation 1.6

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population.

Resolution of fever was defined as body temperature less than or equal to (\<=) 36.6 degree Celsius (°C) (axilla), or \<=37.2°C (oral), or \<=37.8°C (rectal or tympanic) for at least 48 hours without antipyretics/until discharge, whichever was sooner. Time to resolution of fever (in days) was calculated as: date of first occurrence/episode of the event (resolution of fever) - date of first dose + 1. Kaplan-Meier method was used for estimation.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Time to Resolution of Fever	8.0 days Interval 7.0 to 9.0	9.0 days Interval 7.0 to 10.0	7.0 days Interval 6.0 to 12.0

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population.

Time to resolution of fever was defined as body temperature \<=36.6°C (axilla), or \<=37.2 °C (oral), or \<=37.8°C (rectal or tympanic) for at least 48 hours without antipyretics or until discharge, whichever was sooner. Improvement in oxygenation was defined as oxygen saturation (SpO2)/FiO2 of 50 or greater compared to the nadir SpO2/FiO2 for at least 48 hours, or until discharge, whichever was sooner. Nadir SpO2/FiO2 was the nadir (lowest value) at any point in the study. Time to resolution of fever and improvement in oxygenation (in days) was calculated as: date of first occurrence/episode of the event (resolution of fever and improvement in oxygenation) - date of first dose + 1. Kaplan-Meier method was used for estimation.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Time to Resolution of Fever and Improvement in Oxygenation	9.0 days Interval 8.0 to 10.0	10.0 days Interval 9.0 to 13.0	8.0 days Interval 7.0 to 12.0

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population. Here, overall number of participants analyzed = participants evaluable for this outcome measure.

Fever was defined as body temperature greater than (\>) 37.4°C (axilla), or \>38.0 °C (oral), or \>38.4°C (rectal or tympanic) based on maximum value observed during a 24-hour period. Number of days with fever were reported. Least square (LS) mean and standard error (SE) were estimated using the analysis of covariance (ANCOVA) model with treatment group and randomization strata as fixed effects.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=143 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=159 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=77 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Number of Days With Fever	1.2 days Standard Error 0.23	1.3 days Standard Error 0.21	1.8 days Standard Error 0.30

SECONDARY outcome

Timeframe: Baseline, Days 4, 7, 15, 21, and 29

Population: Analysis was performed on mITT population. Here, 'overall number of participants analyzed' = participants evaluable for this outcome measure and 'number analyzed' = participants with available data for each specified category.

NEWS2: used to standardize assessment of acute-illness severity, track clinical condition of participants and to alert clinical teams to participant deterioration. NEWS2 score was based on 7 clinical parameters: respiration rate, oxygen saturation, supplemental oxygen, systolic blood pressure, pulse rate, level of consciousness, and temperature. A score of 0, 1, 2, and 3 was allocated to each parameter except supplemental oxygen (a score of 0 or 1 was allocated) and level of consciousness (a score of 0 or 3 was allocated), where 0 = normal health condition to 3 = worst health condition; higher score indicated more severity. All scores were summed to get an aggregate score. Aggregate NEWS2 score ranged from 0 to 19, with higher scores meaning more severity/higher risk. Percentage of participants in following clinical risk categories were reported: low risk (score 0 to 4); low to medium risk (score of 3 in any individual parameter); medium risk (score 5 to 6); high risk (score 7 to 19).

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=169 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 4: Low	52.8 percentage of participants	56.2 percentage of participants	40.5 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 4: Low to Medium	0.6 percentage of participants	1.2 percentage of participants	0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 7: High	23.0 percentage of participants	26.6 percentage of participants	28.4 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Baseline: Low	28.8 percentage of participants	22.1 percentage of participants	34.2 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Baseline: Low to Medium	0 percentage of participants	0 percentage of participants	0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Baseline: Medium	34.2 percentage of participants	37.4 percentage of participants	27.8 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Baseline: High	37.0 percentage of participants	40.5 percentage of participants	38.0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 4: Medium	19.5 percentage of participants	16.6 percentage of participants	28.6 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 4: High	27.0 percentage of participants	26.0 percentage of participants	31.0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 7: Low	57.0 percentage of participants	60.8 percentage of participants	51.4 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 7: Low to Medium	0 percentage of participants	2.1 percentage of participants	0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 7: Medium	20.0 percentage of participants	10.5 percentage of participants	20.3 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 15: Low	52.5 percentage of participants	52.2 percentage of participants	61.1 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 15: Low to Medium	0 percentage of participants	1.5 percentage of participants	2.8 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 15: Medium	21.3 percentage of participants	19.4 percentage of participants	13.9 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 15: High	26.2 percentage of participants	26.9 percentage of participants	22.2 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 21: Low	44.8 percentage of participants	50.0 percentage of participants	66.7 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 21: Low to Medium	13.8 percentage of participants	0 percentage of participants	0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 21: Medium	24.1 percentage of participants	21.1 percentage of participants	8.3 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 21: High	17.2 percentage of participants	28.9 percentage of participants	25.0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 29: Low	57.1 percentage of participants	27.8 percentage of participants	60.0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 29: Low to Medium	0 percentage of participants	0 percentage of participants	0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 29: Medium	14.3 percentage of participants	27.8 percentage of participants	20.0 percentage of participants
Percentage of Participants in Each National Early Warning Score 2 (NEWS2) Clinical Risk Category at Baseline and at Days 4, 7, 15, 21, and 29 Day 29: High	28.6 percentage of participants	44.4 percentage of participants	20.0 percentage of participants

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population.

Time to NEWS2 \<2 and maintained for 24 hours: time (in days) from 1st dose of study drug until 1st occurrence of NEWS score of \<2 (maintained for 24 hours); calculated as: date of 1st occurrence/episode of event (NEWS score of \<2) - date of 1st dose + 1. NEWS2 score was based on 7 clinical parameters: respiration rate, oxygen saturation, supplemental oxygen, systolic blood pressure, pulse rate, level of consciousness, and temperature. A score of 0, 1, 2, and 3 was allocated to each parameter except supplemental oxygen (score of 0 or 1 was allocated) and level of consciousness (score of 0 or 3 was allocated), where 0=normal health condition to 3=worst health condition; higher score=more severity. All scores were summed to get an aggregate score which ranged from 0 to 19, with higher scores=more severity/higher risk. Kaplan-Meier method was used for analysis.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Time to National Early Warning Score of Less Than (<) 2 and Maintained for 24 Hours	9.0 days Interval 7.0 to 10.0	9.0 days Interval 8.0 to 11.0	11.0 days Interval 8.0 to 14.0

SECONDARY outcome

Timeframe: Baseline, Days 4, 7, 15, 21, and 29

The NEWS2 was used to standardize the assessment of acute-illness severity, track the clinical condition of participants, and to alert clinical teams to participant deterioration. NEWS2 score is based on 7 clinical parameters: respiration rate, oxygen saturation, supplemental oxygen, systolic blood pressure, pulse rate, level of consciousness, and temperature. A score of 0, 1, 2, and 3 was allocated to each parameter except supplemental oxygen (a score of 0 or 1 was allocated) and level of consciousness (a score of 0 or 3 was allocated), where 0 = normal health condition to 3 = worst health condition; higher score indicated more severity. All scores were summed to get an aggregate score. Aggregate NEWS2 score ranged from 0 to 19, with higher scores meaning more severity/higher risk. LS means and SE were estimated using ANCOVA model with treatment group and randomization strata as fixed effects, and baseline NEWS2 score as a covariate.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=146 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=159 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=79 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Change From Baseline at Days 4, 7, 15, 21, and 29 in National Early Warning Score 2 Day 7	-1.63 scores on a scale Standard Error 0.265	-1.47 scores on a scale Standard Error 0.245	-0.83 scores on a scale Standard Error 0.338
Change From Baseline at Days 4, 7, 15, 21, and 29 in National Early Warning Score 2 Day 4	-1.07 scores on a scale Standard Error 0.212	-1.25 scores on a scale Standard Error 0.198	-0.36 scores on a scale Standard Error 0.274
Change From Baseline at Days 4, 7, 15, 21, and 29 in National Early Warning Score 2 Day 15	-2.10 scores on a scale Standard Error 0.508	-1.83 scores on a scale Standard Error 0.467	-2.36 scores on a scale Standard Error 0.641
Change From Baseline at Days 4, 7, 15, 21, and 29 in National Early Warning Score 2 Day 21	-3.02 scores on a scale Standard Error 0.769	-2.24 scores on a scale Standard Error 0.676	-2.96 scores on a scale Standard Error 1.090
Change From Baseline at Days 4, 7, 15, 21, and 29 in National Early Warning Score 2 Day 29	-2.57 scores on a scale Standard Error 0.936	-1.27 scores on a scale Standard Error 0.884	-3.64 scores on a scale Standard Error 1.508

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population.

Time-to-improvement in oxygenation was defined as increase in SpO2/FiO2 of 50 or greater compared to the nadir SpO2/FiO2 for at least 48 hours or until discharge, whichever was sooner. Nadir SpO2/FiO2 was the nadir (lowest value) at any point in the study. Time to improvement in oxygenation was calculated as: date of first occurrence/episode of the event (oxygenation) - date of first dose + 1. Kaplan-Meier method was used for estimation.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Time-to-improvement in Oxygenation	6.0 days Interval 5.0 to 7.0	6.0 days Interval 5.0 to 7.0	7.0 days Interval 5.0 to 8.0

SECONDARY outcome

Timeframe: Day 29

Population: Analysis was performed on mITT population.

Supplemental oxygen was defined as oxygen administration by nasal cannula, simple face mask, or other similar oxygen delivery device.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Participants Alive Off Supplemental Oxygen at Day 29	84.9 percentage of participants	83.8 percentage of participants	86.9 percentage of participants

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population.

Hypoxemia (low level of oxygen in the blood) was defined as SpO2 \<93% on room air, or required supplemental oxygen, or mechanical ventilatory support. Days meeting the criteria for hypoxemia since the first study dose were counted and the percentage of days with hypoxemia were calculated as:100\*number of days with the hypoxemia divided by number of days of follow up (defined as the earlier date of death or discharge or last visit up to Day 29). LS mean and SE were estimated using the ANCOVA model with treatment group and randomization strata as fixed effects.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Days With Hypoxemia	73.01 percentage of days Standard Error 2.063	75.10 percentage of days Standard Error 1.941	76.32 percentage of days Standard Error 2.724

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population.

Supplemental oxygen (oxygen therapy) was defined as oxygen administration using oxygen delivery device (e.g. nasal cannula, simple face mask, non-rebreather mask, high flow nasal cannula, non-invasive ventilation, invasive mechanical ventilation, extracorporeal life support, etc.). Days meeting the criteria for supplemental oxygen use since the first study dose were counted and the percentage of days with supplemental oxygen use were calculated as:100\*number of days with the supplemental oxygen use divided by number of days of follow up (defined as the earlier date of death or discharge or last visit up to Day 29) . LS mean and SE were estimated using the ANCOVA model with treatment group and randomization strata as fixed effects.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Days With Supplemental Oxygen Use	70.57 percentage of days Standard Error 2.082	73.30 percentage of days Standard Error 1.959	73.23 percentage of days Standard Error 2.748

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population. Hence, overall number of participants analyzed = participants evaluable for this outcome measure.

Resting respiratory rate was measured in terms of number of breaths per minute (bpm) while a person is at rest. Only the days with respiratory rate \>24 breath per minute since the first dose were counted and percentage of days with respiratory rate \> 24 bpm were calculated as:100\*number of days with respiratory rate \>24 bpm divided by number of days of follow up (defined as the earlier date of death or discharge or last visit up to Day 29). LS mean and SE were estimated using the ANCOVA model with treatment group and randomization strata as fixed effects.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=150 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=164 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=78 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Days With Resting Respiratory Rate > 24 Breaths Per Minute	14.74 percentage of days Standard Error 1.582	14.58 percentage of days Standard Error 1.485	15.74 percentage of days Standard Error 2.105

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population.

Time to oxygen saturation \>=94% on room air was defined as the time (in days) from first dose of study drug until the time of first occurrence of oxygen saturation \>=94% and it was calculated as: Date of first occurrence/episode of the event (oxygen saturation \>=94%) - date of first dose + 1.Kaplan-Meier method was used for estimation.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Time to Oxygen Saturation >= 94% on Room Air	8.0 days Interval 6.0 to 10.0	8.0 days Interval 8.0 to 11.0	8.0 days Interval 7.0 to 11.0

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population.

Mean number of ventilator free days in participants were reported.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Mean Number of Ventilator Free Days	23.8 days Standard Deviation 9.4	24.0 days Standard Deviation 8.8	24.9 days Standard Deviation 8.6

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population. Here, "overall number of participants analyzed" = participants evaluable for this outcome measure.

Percentage of participants With initiation of mechanical ventilation or non-invasive ventilation, or use of high flow nasal cannula were reported in this outcome measure.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=127 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=141 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=68 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Participants With Initiation of Mechanical Ventilation, Non-invasive Ventilation, or Use of High Flow Nasal Cannula	20.5 percentage of participants	23.4 percentage of participants	19.1 percentage of participants

SECONDARY outcome

Timeframe: Baseline to Day 28

Population: Analysis was performed on mITT population.

Rescue medications were defined as the immunosuppressive (methylprednisolone, dexamethasone and prednisone) therapies. During the course of the study, participant who required rescue therapy was based on the judgement of the study physician.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Participants Who Required Rescue Medication	13.8 percentage of participants	15.0 percentage of participants	22.6 percentage of participants

SECONDARY outcome

Timeframe: Baseline to Day 29

Population: Analysis was performed on mITT population. Here, "overall number of participants analyzed"=participants evaluable for this outcome measure.

Percentage of participants who needed ICU care until Day 29 were reported for those not in an ICU at baseline.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=98 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=114 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=56 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Percentage of Participants Who Needed Intensive Care Unit (ICU) Care During Study	11.2 percentage of participants	14.9 percentage of participants	12.5 percentage of participants

SECONDARY outcome

Timeframe: At Day 60

Population: Analysis was performed on mITT population. Here, "overall number of participants analyzed"=participants evaluable for this outcome measure.

Number of days of hospitalization among alive participants were counted at Day 60 since the first dose. LS mean and SE were estimated using the ANCOVA model with treatment group and randomization strata as fixed effects.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=142 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=155 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=75 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Number of Days of Hospitalization Among Survivors (Alive Participants)	15.6 days Standard Error 0.96	16.1 days Standard Error 0.91	15.9 days Standard Error 1.27

SECONDARY outcome

Timeframe: Baseline up to 60 days

Population: Analysis was performed on safety population which included all randomized participants who were treated with the study medication and were analyzed according to the actual treatment received.

An adverse event (AE) was defined as any untoward medical occurrence in a participant who received study drug and did not necessarily had to have a causal relationship with the treatment. Treatment-emergent AEs (TEAEs) were the AEs that developed or worsened or became serious during the TEAE period (from the time of first dose of study drug to the last dose of study drug + 60 days). SAEs were any untoward medical occurrence that resulted in any of the following outcomes: death, life-threatening, required initial or prolonged in-patient hospitalization, persistent or significant disability/incapacity, congenital anomaly/birth defect, or considered as medically important event.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Number of Participants With Treatment-emergent Serious Adverse Events (SAEs)	42 Participants	51 Participants	20 Participants

SECONDARY outcome

Timeframe: Baseline up to 60 days

Population: Analysis was performed on safety population.

Major or opportunistic bacterial or fungal infections was considered as an adverse event of special interest (AESI: defined as an AE \[serious or non-serious\] of scientific and medical concern specific to the Sponsor's product or program, for which ongoing monitoring and immediate notification by the Investigator to the Sponsor was required).

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Number of Participants With Major or Opportunistic Bacterial or Fungal Infections	8 Participants	15 Participants	3 Participants

SECONDARY outcome

Timeframe: Baseline up to 60 days

Population: Analysis was performed on safety population. Here, 'number analyzed' = participants with available data for each specified category and "0" in the number analyzed field signifies that no participants had Grade 4 neutropenia and therefore were not evaluable.

Grade 4 neutropenia was defined as participants with absolute neutrophil count (ANC) \<500 per cubic millimeter (mm\^3). Grade 4 neutropenia with concurrent invasive infection was defined as infections and infestations (in participants with Grade 4 neutropenia) within 1 week of ANC \<500/mm\^3 and was considered as an AESI (defined as an AE \[serious or non-serious\] of scientific and medical concern specific to the Sponsor's product or program, for which ongoing monitoring and immediate notification by the Investigator to the Sponsor was required).

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Number of Participants With Grade 4 Neutropenia and Grade 4 Neutropenia With Concurrent Invasive Infection Grade 4 neutropenia with concurrent invasive infection	0 Participants	0 Participants	—
Number of Participants With Grade 4 Neutropenia and Grade 4 Neutropenia With Concurrent Invasive Infection Grade 4 neutropenia	3 Participants	6 Participants	0 Participants

SECONDARY outcome

Timeframe: Baseline up to 60 days

Population: Analysis was performed on safety population.

Grade \>=2 (moderate) infusion related reactions (defined as any TEAE signs or symptoms experienced by participants who received study medication within 24 hours of the start of infusion) and Grade \>=2 (moderate) hypersensitivity reactions (anaphylactic reaction, hypersensitivity or angioedema and moderate reactions) were considered as AESI which was defined as an AE (serious or non-serious) of scientific and medical concern specific to the Sponsor's product or program, for which ongoing monitoring and immediate notification by the Investigator to the Sponsor was required. Gastrointestinal Perforation was defined as formation of a hole through the stomach, large bowel or small intestine.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=159 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Number of Participants With Grade >=2 Infusion Reactions, Grade >=2 Hypersensitivity Reactions and Gastrointestinal Perforation Grade >=2 Infusion related reactions	1 Participants	6 Participants	0 Participants
Number of Participants With Grade >=2 Infusion Reactions, Grade >=2 Hypersensitivity Reactions and Gastrointestinal Perforation Gastrointestinal perforation	1 Participants	0 Participants	0 Participants
Number of Participants With Grade >=2 Infusion Reactions, Grade >=2 Hypersensitivity Reactions and Gastrointestinal Perforation Grade >=2 Hypersensitivity reactions	1 Participants	7 Participants	0 Participants

SECONDARY outcome

Timeframe: Baseline up to 60 days

Population: Analysis was performed on safety population. Here, overall number of participants analyzed = participants with available data for this outcome measure.

Criteria for PCSA: * Hemoglobin: less than or equal to (\<=) 115 grams per liter (g/L) (male) and \<=95 g/L (female); greater than or equal to (\>=) 185 g/L (male) and \>=165 g/L (female); and decrease from baseline \>=20 g/L. * Leukocytes: \<3.0\*10\^9/Liters (L) (Non-Black) or \<2.0\*10\^9/L (black); \>=16.0\*10\^9/L. * Platelets: \< 100\*10\^9/L; \>=700\*10\^9/L.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=156 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=170 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities (PCSA): Hematological Parameter - Hemoglobin, Leukocytes and Platelets Hemoglobin >=185 g/L (male) and >=165 g/L (female)	0 Participants	0 Participants	0 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities (PCSA): Hematological Parameter - Hemoglobin, Leukocytes and Platelets Leukocytes >=16*10^9/L	13 Participants	21 Participants	6 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities (PCSA): Hematological Parameter - Hemoglobin, Leukocytes and Platelets Platelets >=700*10^9/L	3 Participants	2 Participants	2 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities (PCSA): Hematological Parameter - Hemoglobin, Leukocytes and Platelets Hemoglobin <=115 g/L (male) and <=95 g/L (female)	29 Participants	34 Participants	15 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities (PCSA): Hematological Parameter - Hemoglobin, Leukocytes and Platelets Hemoglobin decrease from baseline >=20 g/L	32 Participants	30 Participants	15 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities (PCSA): Hematological Parameter - Hemoglobin, Leukocytes and Platelets Leukocytes <3.010^9/L (Non-Black) or <2.010^9/L (black)	19 Participants	31 Participants	1 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities (PCSA): Hematological Parameter - Hemoglobin, Leukocytes and Platelets Platelets <100*10^9/L	2 Participants	7 Participants	3 Participants

SECONDARY outcome

Timeframe: Baseline up to 60 days

Population: Analysis was performed on safety population. Here, overall number of participants analyzed = participants with available data for this outcome measure.

Criteria for PCSA: Creatinine: \>=150 micromoles per liter (mcmol/L); \>=30% change from baseline; \>= 100% change from baseline.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=156 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=170 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities: Renal Function Parameters Creatinine >=150 mcmol/L	15 Participants	15 Participants	5 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities: Renal Function Parameters >=30% change from baseline in Creatinine	31 Participants	30 Participants	10 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities: Renal Function Parameters >=100% change from baseline in Creatinine	6 Participants	7 Participants	3 Participants

SECONDARY outcome

Timeframe: Baseline up to 60 days

Population: Analysis was performed on safety population. Here, 'overall number of participants analyzed' = participants evaluable for this outcome measure and 'number analyzed' = participants with available data for each specified category.

* Alanine Aminotransferase (ALT): \>3 upper limit of normal (ULN); \>5 ULN; \>10 ULN and \>20 ULN. * Bilirubin: \>1.5 ULN; \>2 ULN.

Outcome measures

Outcome measures
Measure	Sarilumab 200 mg n=156 Participants Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=169 Participants Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 Participants Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities: Liver Function Parameters Bilirubin >2 ULN	4 Participants	2 Participants	2 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities: Liver Function Parameters ALT >3 ULN	60 Participants	63 Participants	24 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities: Liver Function Parameters ALT >5 ULN	28 Participants	25 Participants	12 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities: Liver Function Parameters ALT >10 ULN	6 Participants	5 Participants	3 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities: Liver Function Parameters ALT >20 ULN	1 Participants	0 Participants	0 Participants
Number of Participants With Potentially Clinically Significant Laboratory Abnormalities: Liver Function Parameters Bilirubin >1.5 ULN	5 Participants	4 Participants	4 Participants

Adverse Events

Sarilumab 200 mg

Serious events: 42 serious events

Other events: 57 other events

Deaths: 17 deaths

Sarilumab 400 mg

Serious events: 51 serious events

Other events: 68 other events

Deaths: 18 deaths

Placebo

Serious events: 20 serious events

Other events: 14 other events

Deaths: 9 deaths

Serious adverse events

Other adverse events

Other adverse events
Measure	Sarilumab 200 mg n=159 participants at risk Sarilumab 200 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 200 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Sarilumab 400 mg n=173 participants at risk Sarilumab 400 mg, single dose of IV injection on Day 1. Participants could receive a second dose of sarilumab 400 mg 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.	Placebo n=84 participants at risk Placebo (for sarilumab), single dose of IV injection on Day 1. Participants could receive a second dose of placebo (for sarilumab) 24 to 48 hours after the first dose if first and any one of last three criteria was met as compared to Day 1 (as per following protocol amendment 2 \[dated 08-Apr-2020\]): * Benefit risk assessment by the investigator favored the administration of another dose of study drug without compromising safety and * Increase/recurrence of fever or * Increase/no change in FiO2 requirement or * Required vasopressors, ECMO or development of multi-organ dysfunction.
Blood and lymphatic system disorders Neutropenia	6.9% 11/159 • Number of events 11 • All AEs were collected from the time of first dose of study drug up to 60 days regardless of seriousness or relationship to study drug. Reported AEs and deaths were TEAEs that developed/worsened in grade or became serious during 'treatment-emergent adverse event period' (from the time of first dose of study drug to the last dose of study drug + 60 days). Analysis was performed on safety population.	7.5% 13/173 • Number of events 13 • All AEs were collected from the time of first dose of study drug up to 60 days regardless of seriousness or relationship to study drug. Reported AEs and deaths were TEAEs that developed/worsened in grade or became serious during 'treatment-emergent adverse event period' (from the time of first dose of study drug to the last dose of study drug + 60 days). Analysis was performed on safety population.	0.00% 0/84 • All AEs were collected from the time of first dose of study drug up to 60 days regardless of seriousness or relationship to study drug. Reported AEs and deaths were TEAEs that developed/worsened in grade or became serious during 'treatment-emergent adverse event period' (from the time of first dose of study drug to the last dose of study drug + 60 days). Analysis was performed on safety population.
Investigations Alanine Aminotransferase Increased	30.2% 48/159 • Number of events 48 • All AEs were collected from the time of first dose of study drug up to 60 days regardless of seriousness or relationship to study drug. Reported AEs and deaths were TEAEs that developed/worsened in grade or became serious during 'treatment-emergent adverse event period' (from the time of first dose of study drug to the last dose of study drug + 60 days). Analysis was performed on safety population.	33.5% 58/173 • Number of events 59 • All AEs were collected from the time of first dose of study drug up to 60 days regardless of seriousness or relationship to study drug. Reported AEs and deaths were TEAEs that developed/worsened in grade or became serious during 'treatment-emergent adverse event period' (from the time of first dose of study drug to the last dose of study drug + 60 days). Analysis was performed on safety population.	16.7% 14/84 • Number of events 14 • All AEs were collected from the time of first dose of study drug up to 60 days regardless of seriousness or relationship to study drug. Reported AEs and deaths were TEAEs that developed/worsened in grade or became serious during 'treatment-emergent adverse event period' (from the time of first dose of study drug to the last dose of study drug + 60 days). Analysis was performed on safety population.
Investigations Aspartate Aminotransferase Increased	6.9% 11/159 • Number of events 11 • All AEs were collected from the time of first dose of study drug up to 60 days regardless of seriousness or relationship to study drug. Reported AEs and deaths were TEAEs that developed/worsened in grade or became serious during 'treatment-emergent adverse event period' (from the time of first dose of study drug to the last dose of study drug + 60 days). Analysis was performed on safety population.	8.7% 15/173 • Number of events 16 • All AEs were collected from the time of first dose of study drug up to 60 days regardless of seriousness or relationship to study drug. Reported AEs and deaths were TEAEs that developed/worsened in grade or became serious during 'treatment-emergent adverse event period' (from the time of first dose of study drug to the last dose of study drug + 60 days). Analysis was performed on safety population.	0.00% 0/84 • All AEs were collected from the time of first dose of study drug up to 60 days regardless of seriousness or relationship to study drug. Reported AEs and deaths were TEAEs that developed/worsened in grade or became serious during 'treatment-emergent adverse event period' (from the time of first dose of study drug to the last dose of study drug + 60 days). Analysis was performed on safety population.

Additional Information

Trial Transparency Team

Sanofi

Phone: 800-633-1610

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee The Sponsor supports publication of clinical trial results but may request that investigators temporarily delay or alter publications in order to protect proprietary information. The Sponsor may also require that the results of multicenter studies be published only in their entirety and not as individual site data.
Publication restrictions are in place

Restriction type: OTHER