Trial Outcomes & Findings for Flublok v. Standard Dose Vaccine Effectiveness Among Kaiser Permanente Northern California Adults 18-64 Years (NCT NCT03694392)

Last Updated: 2025-04-08

Results Overview

Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had a PCR-confirmed positive influenza test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).

Recruitment status

COMPLETED

Target enrollment

2776278 participants

Primary outcome timeframe

Up to 8 months

Results posted on

2025-04-08

Participant Flow

Participant milestones

Participant milestones
Measure	Flublok Recipients Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.	SD-IIV Recipients Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.
Overall Study STARTED	1018043	1758235
Overall Study COMPLETED	632962	997366
Overall Study NOT COMPLETED	385081	760869

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Flublok v. Standard Dose Vaccine Effectiveness Among Kaiser Permanente Northern California Adults 18-64 Years

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Flublok Recipients n=632962 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.	SD-IIV Recipients n=997366 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Total n=1630328 Participants Total of all reporting groups
Age, Categorical <=18 years	0 Participants n=93 Participants	0 Participants n=4 Participants	0 Participants n=27 Participants
Age, Categorical Between 18 and 65 years	632962 Participants n=93 Participants	997366 Participants n=4 Participants	1630328 Participants n=27 Participants
Age, Categorical >=65 years	0 Participants n=93 Participants	0 Participants n=4 Participants	0 Participants n=27 Participants
Sex: Female, Male Female	363921 Participants n=93 Participants	585482 Participants n=4 Participants	949403 Participants n=27 Participants
Sex: Female, Male Male	269041 Participants n=93 Participants	411884 Participants n=4 Participants	680925 Participants n=27 Participants
Race/Ethnicity, Customized White	275117 Participants n=93 Participants	420570 Participants n=4 Participants	695687 Participants n=27 Participants
Race/Ethnicity, Customized Black	27601 Participants n=93 Participants	45674 Participants n=4 Participants	73275 Participants n=27 Participants
Race/Ethnicity, Customized Asian	159104 Participants n=93 Participants	255008 Participants n=4 Participants	414112 Participants n=27 Participants
Race/Ethnicity, Customized Pacific Islander	4824 Participants n=93 Participants	7499 Participants n=4 Participants	12323 Participants n=27 Participants
Race/Ethnicity, Customized Native American	2908 Participants n=93 Participants	4635 Participants n=4 Participants	7543 Participants n=27 Participants
Race/Ethnicity, Customized Multiracial	16229 Participants n=93 Participants	25946 Participants n=4 Participants	42175 Participants n=27 Participants
Race/Ethnicity, Customized Unknown/Other	147179 Participants n=93 Participants	238034 Participants n=4 Participants	385213 Participants n=27 Participants
Region of Enrollment United States	632962 participants n=93 Participants	997366 participants n=4 Participants	1630328 participants n=27 Participants
History of asthma	86127 Participants n=93 Participants	132550 Participants n=4 Participants	218677 Participants n=27 Participants
History of diabetes	67026 Participants n=93 Participants	97192 Participants n=4 Participants	164218 Participants n=27 Participants
History of chronic obstructive pulmonary disease	6174 Participants n=93 Participants	8563 Participants n=4 Participants	14737 Participants n=27 Participants
History of coronary heart disease	11947 Participants n=93 Participants	16902 Participants n=4 Participants	28849 Participants n=27 Participants
Receipt of influenza vaccine in previous year	414500 Participants n=93 Participants	640263 Participants n=4 Participants	1054763 Participants n=27 Participants
Charlson Comorbidity Index No Charlson comorbidities	508118 Participants n=93 Participants	812879 Participants n=4 Participants	1320997 Participants n=27 Participants
Charlson Comorbidity Index CCI=1	81980 Participants n=93 Participants	122562 Participants n=4 Participants	204542 Participants n=27 Participants
Charlson Comorbidity Index CCI≥2	42864 Participants n=93 Participants	61925 Participants n=4 Participants	104789 Participants n=27 Participants
Body mass index 0 - < 18.5 kg/m²	7819 Participants n=93 Participants	12311 Participants n=4 Participants	20130 Participants n=27 Participants
Body mass index 18.5 - < 25 kg/m²	188431 Participants n=93 Participants	306194 Participants n=4 Participants	494625 Participants n=27 Participants
Body mass index 25 - < 30 kg/m²	206663 Participants n=93 Participants	323624 Participants n=4 Participants	530287 Participants n=27 Participants
Body mass index ≥ 30 kg/m²	209817 Participants n=93 Participants	321607 Participants n=4 Participants	531424 Participants n=27 Participants
Body mass index None	20232 Participants n=93 Participants	33630 Participants n=4 Participants	53862 Participants n=27 Participants
Number of weeks with outpatient visits in prior year 0	57602 Participants n=93 Participants	92349 Participants n=4 Participants	149951 Participants n=27 Participants
Number of weeks with outpatient visits in prior year 1-3	270701 Participants n=93 Participants	427043 Participants n=4 Participants	697744 Participants n=27 Participants
Number of weeks with outpatient visits in prior year 4-7	165444 Participants n=93 Participants	256965 Participants n=4 Participants	422409 Participants n=27 Participants
Number of weeks with outpatient visits in prior year ≥8	139215 Participants n=93 Participants	221009 Participants n=4 Participants	360224 Participants n=27 Participants
Number of inpatient stays in prior year 0	573712 Participants n=93 Participants	902365 Participants n=4 Participants	1476077 Participants n=27 Participants
Number of inpatient stays in prior year 1	44860 Participants n=93 Participants	71208 Participants n=4 Participants	116068 Participants n=27 Participants
Number of inpatient stays in prior year 2	9707 Participants n=93 Participants	15896 Participants n=4 Participants	25603 Participants n=27 Participants
Number of inpatient stays in prior year 3	2885 Participants n=93 Participants	4735 Participants n=4 Participants	7620 Participants n=27 Participants
Number of inpatient stays in prior year ≥4	1798 Participants n=93 Participants	3162 Participants n=4 Participants	4960 Participants n=27 Participants
Prior membership <1 year	78004 Participants n=93 Participants	127160 Participants n=4 Participants	205164 Participants n=27 Participants
Prior membership 1 to <2 years	62407 Participants n=93 Participants	100315 Participants n=4 Participants	162722 Participants n=27 Participants
Prior membership 2 to <3 years	52678 Participants n=93 Participants	84938 Participants n=4 Participants	137616 Participants n=27 Participants
Prior membership 3 to <4 years	45919 Participants n=93 Participants	74028 Participants n=4 Participants	119947 Participants n=27 Participants
Prior membership 4 to <5 years	41545 Participants n=93 Participants	66292 Participants n=4 Participants	107837 Participants n=27 Participants
Prior membership ≥5 years	352409 Participants n=93 Participants	544633 Participants n=4 Participants	897042 Participants n=27 Participants

PRIMARY outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=395852 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=279400 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 50-64 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza Tests	925 participants	559 participants

SECONDARY outcome

Timeframe: Up to 8 months

Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had an inpatient stay and had a PCR-confirmed positive influenza test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=395852 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=279400 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 50-64 Years Old Hospitalized With PCR-confirmed Influenza	153 participants	95 participants

SECONDARY outcome

Timeframe: Up to 8 months

Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had an inpatient stay for community-acquired pneumonia (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=395852 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=279400 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 50-64 Years Old Hospitalized With Community-acquired Pneumonia	183 Participants	106 Participants

SECONDARY outcome

Timeframe: Up to 8 months

Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had an inpatient stay for cardio-respiratory events (e.g., pneumonia, other lower respiratory infections, acute myocardial infarction, congestive heart failure, stroke) (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=395852 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=279400 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 50-64 Years Old Hospitalized With Cardio-respiratory Events	890 Participants	631 Participants

SECONDARY outcome

Timeframe: Up to 8 months

Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had a PCR-confirmed positive influenza A test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=395852 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=279400 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 50-64 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza A Tests	862 participants	522 participants

SECONDARY outcome

Timeframe: Up to 8 months

Patients who receive either Flublok or SD-IIV will be retroactively assessed for whether they had a PCR-confirmed positive influenza B test (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30).

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=395852 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=279400 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 50-64 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza B Tests	64 participants	37 participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=601514 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=353562 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 18-49 Years Old Hospitalized With Community-acquired Pneumonia	49 Participants	37 Participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Patients who receive either Flublok or SD-IIV will be retroactively assessed (≥14 days after vaccination) as recorded in their electronic medical record by the end of the influenza season (April 30) for influenza-like illness (ILI) International Classification of Diseases, 10th Edition (and absence of a negative lab-confirmed influenza)

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=395852 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=279400 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 50-64 Years Old With Influenza-Like Illness (ILI)	2871 Participants	1826 Participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=395852 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=279400 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 50-64 Years Old With All-Cause-Hospitalizations	6005 Participants	4308 Participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=395852 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=279400 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 50-64 Years Old With All-Cause Mortality	422 Participants	286 Participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=601514 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=353562 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 18-49 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza Tests	1510 participants	827 participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=601514 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=353562 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 18-49 Years Old Hospitalized With PCR-confirmed Influenza	88 participants	48 participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=601514 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=353562 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 18-49 Years Old Hospitalized With Cardio-respiratory Events	208 Participants	133 Participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=601514 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=353562 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 18-49 Years Old With Influenza-Like Illness (ILI)	5434 Participants	2904 Participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=601514 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=353562 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 18-49 Years Old With All-Cause-Hospitalizations	2950 Participants	1858 Participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=601514 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=353562 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 18-49 Years Old With All-Cause Mortality	79 Participants	66 Participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=601514 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=353562 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 18-49 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza A Tests	1282 participants	682 participants

OTHER_PRE_SPECIFIED outcome

Timeframe: Up to 8 months

Outcome measures

Outcome measures
Measure	SD-IIV Recipients n=601514 Participants Kaiser Permanente Northern California members aged 18-64 years who receive standard dose inactivated influenza vaccine (SD-IIV). Standard Dose Inactivated Influenza Vaccine (SD-IIV): For the 2018-2019, 2019-2020, and 2020-2021 flu seasons, the primary SD-IIVs used will be Fluarix Quadrivalent and Flulaval Quadrivalent.	Flublok Recipients n=353562 Participants Kaiser Permanente Northern California members aged 18-64 years who receive Flublok Quadrivalent vaccine. Flublok Quadrivalent: Flublok Quadrivalent vaccine is a recombinant hemagglutinin influenza vaccine indicated for active immunization against disease caused by influenza A subtype viruses and type B viruses contained in the vaccine for adults 18 years of age and older. Use of recombinant DNA techniques to produce vaccine antigen expressed in cell culture is a method that avoids growing the influenza viruses in embryonated hen's eggs.
Number of Adults 18-49 Years Old With Polymerase-chain Reaction (PCR) Confirmed Influenza B Tests	231 participants	146 participants

Adverse Events

Flublok Recipients

Serious events: 0 serious events

Other events: 0 other events

Deaths: 352 deaths

SD-IIV Recipients

Serious events: 0 serious events

Other events: 0 other events

Deaths: 501 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Amber Hsiao Hyman, Senior Research Project Manger

Kaiser Permanente Vaccine Study Center

Phone: 510-267-7517

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place