Trial Outcomes & Findings for A Study to Assess the Safety and Immune Response of a Vaccine Against Influenza in Healthy Younger and Older Adults (NCT NCT05823974)

Last Updated: 2025-07-23

Results Overview

Clinically significant abnormal laboratory findings are those which are not associated with an underlying disease, unless judged by the investigator to be more severe than expected for the participants condition. Normal or missing values refer to laboratory values that were within normal range or missing at baseline.

Recruitment status

COMPLETED

Study phase

PHASE1/PHASE2

Target enrollment

1275 participants

Primary outcome timeframe

At Day 29 compared to baseline (Day 1)

Results posted on

2025-07-23

Participant Flow

A total of 1275 participants were included in Enrolled set, out of which only 1256 were included in Exposed set and started the study.

Participant milestones

Participant milestones
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Overall Study STARTED	21	22	23	23	22	25	23	22	23	22	23	21	23	115	108	137	120	119	122	125	117
Overall Study COMPLETED	20	17	18	22	19	21	20	20	20	20	21	21	20	111	105	131	119	116	119	123	116
Overall Study NOT COMPLETED	1	5	5	1	3	4	3	2	3	2	2	0	3	4	3	6	1	3	3	2	1

Reasons for withdrawal

Reasons for withdrawal
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Control Ph1_YA Group YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Overall Study Lost to Follow-up	0	3	1	0	1	0	1	0	0	1	1	1	2	1	1	1	0	0	2	0
Overall Study Physician Decision	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0	1	1	0	0
Overall Study Withdrawal by Subject	1	1	2	0	2	3	1	1	2	1	1	0	1	1	3	0	2	2	0	1
Overall Study MIGRATED / MOVED FROM THE STUDY AREA	0	0	1	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0	0
Overall Study Other	0	1	1	1	0	1	1	1	1	0	0	2	1	0	1	0	0	0	0	0

Baseline Characteristics

A Study to Assess the Safety and Immune Response of a Vaccine Against Influenza in Healthy Younger and Older Adults

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group n=21 Participants YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group n=25 Participants YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group n=23 Participants YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group n=23 Participants YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group n=115 Participants YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group n=108 Participants YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group n=137 Participants YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group n=120 Participants YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group n=119 Participants OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group n=122 Participants OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group n=125 Participants OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group n=117 Participants OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.	Total n=1256 Participants Total of all reporting groups
Age, Customized 18 - 64 years	21 Participants n=5 Participants	22 Participants n=7 Participants	23 Participants n=5 Participants	23 Participants n=4 Participants	22 Participants n=21 Participants	25 Participants n=8 Participants	23 Participants n=8 Participants	22 Participants n=24 Participants	23 Participants n=42 Participants	22 Participants n=42 Participants	23 Participants n=42 Participants	21 Participants n=42 Participants	23 Participants n=36 Participants	114 Participants n=36 Participants	108 Participants n=24 Participants	137 Participants n=135 Participants	120 Participants n=136 Participants	1 Participants n=44 Participants	0 Participants n=667 Participants	0 Participants n=15 Participants	0 Participants n=40 Participants	773 Participants n=40 Participants
Age, Customized 65 - 84 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=36 Participants	1 Participants n=36 Participants	0 Participants n=24 Participants	0 Participants n=135 Participants	0 Participants n=136 Participants	118 Participants n=44 Participants	121 Participants n=667 Participants	124 Participants n=15 Participants	117 Participants n=40 Participants	481 Participants n=40 Participants
Age, Customized ≥ 85 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=36 Participants	0 Participants n=36 Participants	0 Participants n=24 Participants	0 Participants n=135 Participants	0 Participants n=136 Participants	0 Participants n=44 Participants	1 Participants n=667 Participants	1 Participants n=15 Participants	0 Participants n=40 Participants	2 Participants n=40 Participants
Sex: Female, Male Female	12 Participants n=5 Participants	11 Participants n=7 Participants	15 Participants n=5 Participants	13 Participants n=4 Participants	13 Participants n=21 Participants	13 Participants n=8 Participants	11 Participants n=8 Participants	13 Participants n=24 Participants	13 Participants n=42 Participants	11 Participants n=42 Participants	12 Participants n=42 Participants	13 Participants n=42 Participants	8 Participants n=36 Participants	65 Participants n=36 Participants	55 Participants n=24 Participants	86 Participants n=135 Participants	70 Participants n=136 Participants	69 Participants n=44 Participants	55 Participants n=667 Participants	61 Participants n=15 Participants	71 Participants n=40 Participants	690 Participants n=40 Participants
Sex: Female, Male Male	9 Participants n=5 Participants	11 Participants n=7 Participants	8 Participants n=5 Participants	10 Participants n=4 Participants	9 Participants n=21 Participants	12 Participants n=8 Participants	12 Participants n=8 Participants	9 Participants n=24 Participants	10 Participants n=42 Participants	11 Participants n=42 Participants	11 Participants n=42 Participants	8 Participants n=42 Participants	15 Participants n=36 Participants	50 Participants n=36 Participants	53 Participants n=24 Participants	51 Participants n=135 Participants	50 Participants n=136 Participants	50 Participants n=44 Participants	67 Participants n=667 Participants	64 Participants n=15 Participants	46 Participants n=40 Participants	566 Participants n=40 Participants
Race/Ethnicity, Customized WHITE	14 Participants n=5 Participants	19 Participants n=7 Participants	19 Participants n=5 Participants	18 Participants n=4 Participants	16 Participants n=21 Participants	18 Participants n=8 Participants	16 Participants n=8 Participants	19 Participants n=24 Participants	17 Participants n=42 Participants	15 Participants n=42 Participants	17 Participants n=42 Participants	13 Participants n=42 Participants	19 Participants n=36 Participants	94 Participants n=36 Participants	91 Participants n=24 Participants	116 Participants n=135 Participants	96 Participants n=136 Participants	88 Participants n=44 Participants	95 Participants n=667 Participants	101 Participants n=15 Participants	87 Participants n=40 Participants	988 Participants n=40 Participants
Race/Ethnicity, Customized All other Races	5 Participants n=5 Participants	2 Participants n=7 Participants	4 Participants n=5 Participants	5 Participants n=4 Participants	6 Participants n=21 Participants	6 Participants n=8 Participants	7 Participants n=8 Participants	3 Participants n=24 Participants	6 Participants n=42 Participants	7 Participants n=42 Participants	6 Participants n=42 Participants	8 Participants n=42 Participants	4 Participants n=36 Participants	19 Participants n=36 Participants	15 Participants n=24 Participants	19 Participants n=135 Participants	17 Participants n=136 Participants	25 Participants n=44 Participants	22 Participants n=667 Participants	19 Participants n=15 Participants	21 Participants n=40 Participants	226 Participants n=40 Participants
Race/Ethnicity, Customized MULTIPLE	0 Participants n=5 Participants	1 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	1 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=36 Participants	1 Participants n=36 Participants	0 Participants n=24 Participants	0 Participants n=135 Participants	3 Participants n=136 Participants	1 Participants n=44 Participants	1 Participants n=667 Participants	0 Participants n=15 Participants	1 Participants n=40 Participants	9 Participants n=40 Participants
Race/Ethnicity, Customized NOT REPORTED	2 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=36 Participants	1 Participants n=36 Participants	1 Participants n=24 Participants	2 Participants n=135 Participants	3 Participants n=136 Participants	5 Participants n=44 Participants	4 Participants n=667 Participants	5 Participants n=15 Participants	8 Participants n=40 Participants	31 Participants n=40 Participants
Race/Ethnicity, Customized UNKNOWN	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=36 Participants	0 Participants n=36 Participants	1 Participants n=24 Participants	0 Participants n=135 Participants	1 Participants n=136 Participants	0 Participants n=44 Participants	0 Participants n=667 Participants	0 Participants n=15 Participants	0 Participants n=40 Participants	2 Participants n=40 Participants

PRIMARY outcome

Timeframe: Day 1 to Day 7

Population: The analysis was performed on the Exposed Set (ES), which included all participants who received a study intervention and for whom solicited administration site events data were available at specified timepoints.

Assessed solicited administration site events included pain, redness (Erythema), swelling, lymphadenopathy (defined as localized axillary, cervical or supraclavicular swelling or tenderness ipsilateral to the injection arm). Any = occurrence of the event regardless of intensity grade or relation to the study vaccination.

Outcome measures

Outcome measures
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group n=21 Participants YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group n=25 Participants YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group n=23 Participants YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group n=23 Participants YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group n=115 Participants YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group n=108 Participants YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group n=137 Participants YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group n=120 Participants YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group n=119 Participants OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group n=122 Participants OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group n=125 Participants OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group n=117 Participants OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Number of Participants Reporting Any Solicited Administration Site Adverse Events (AEs) Lymphadenopathy	6 Participants	10 Participants	8 Participants	10 Participants	10 Participants	14 Participants	5 Participants	9 Participants	8 Participants	10 Participants	8 Participants	11 Participants	2 Participants	28 Participants	41 Participants	53 Participants	14 Participants	20 Participants	19 Participants	14 Participants	10 Participants
Number of Participants Reporting Any Solicited Administration Site Adverse Events (AEs) Erythema	0 Participants	2 Participants	2 Participants	2 Participants	3 Participants	4 Participants	1 Participants	1 Participants	1 Participants	3 Participants	3 Participants	3 Participants	2 Participants	3 Participants	5 Participants	8 Participants	1 Participants	6 Participants	6 Participants	9 Participants	4 Participants
Number of Participants Reporting Any Solicited Administration Site Adverse Events (AEs) Pain	15 Participants	19 Participants	21 Participants	20 Participants	19 Participants	22 Participants	15 Participants	19 Participants	18 Participants	19 Participants	21 Participants	18 Participants	13 Participants	82 Participants	86 Participants	118 Participants	53 Participants	63 Participants	64 Participants	78 Participants	41 Participants
Number of Participants Reporting Any Solicited Administration Site Adverse Events (AEs) Swelling	0 Participants	1 Participants	0 Participants	1 Participants	1 Participants	2 Participants	1 Participants	2 Participants	3 Participants	0 Participants	3 Participants	3 Participants	2 Participants	3 Participants	7 Participants	7 Participants	1 Participants	6 Participants	5 Participants	8 Participants	6 Participants

PRIMARY outcome

Timeframe: Day 1 to Day 7

Population: The analysis was performed on the ES, which included all participants who received a study intervention and for whom solicited systemic events data were available at specified timepoints.

Assessed solicited systemic events included fever (defined as axillary temperature greater than or equal to (\>=) 38.0°C/100.4°F), chills, headache, fatigue, myalgia, and arthralgia. Any = occurrence of the event regardless of intensity grade or relation to the study vaccination.

Outcome measures

Outcome measures
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group n=21 Participants YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group n=25 Participants YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group n=23 Participants YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group n=23 Participants YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group n=115 Participants YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group n=108 Participants YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group n=137 Participants YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group n=120 Participants YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group n=119 Participants OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group n=122 Participants OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group n=125 Participants OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group n=117 Participants OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Number of Participants Reporting Any Solicited Systemic AEs Arthralgia	3 Participants	12 Participants	8 Participants	10 Participants	11 Participants	10 Participants	9 Participants	11 Participants	11 Participants	7 Participants	9 Participants	10 Participants	0 Participants	31 Participants	37 Participants	48 Participants	11 Participants	15 Participants	27 Participants	33 Participants	9 Participants
Number of Participants Reporting Any Solicited Systemic AEs Chills	4 Participants	12 Participants	11 Participants	14 Participants	10 Participants	9 Participants	15 Participants	15 Participants	12 Participants	12 Participants	20 Participants	13 Participants	0 Participants	30 Participants	39 Participants	73 Participants	18 Participants	18 Participants	19 Participants	37 Participants	7 Participants
Number of Participants Reporting Any Solicited Systemic AEs Fatigue	10 Participants	19 Participants	17 Participants	18 Participants	17 Participants	18 Participants	16 Participants	19 Participants	17 Participants	16 Participants	18 Participants	17 Participants	9 Participants	58 Participants	70 Participants	103 Participants	49 Participants	44 Participants	51 Participants	64 Participants	26 Participants
Number of Participants Reporting Any Solicited Systemic AEs Headache	11 Participants	17 Participants	15 Participants	17 Participants	16 Participants	17 Participants	15 Participants	17 Participants	14 Participants	16 Participants	17 Participants	13 Participants	5 Participants	54 Participants	58 Participants	99 Participants	36 Participants	36 Participants	36 Participants	50 Participants	19 Participants
Number of Participants Reporting Any Solicited Systemic AEs Temperature	1 Participants	2 Participants	6 Participants	10 Participants	4 Participants	1 Participants	8 Participants	5 Participants	7 Participants	5 Participants	9 Participants	6 Participants	0 Participants	5 Participants	8 Participants	25 Participants	2 Participants	1 Participants	5 Participants	14 Participants	2 Participants
Number of Participants Reporting Any Solicited Systemic AEs Myalgia	10 Participants	21 Participants	15 Participants	18 Participants	15 Participants	19 Participants	15 Participants	16 Participants	16 Participants	18 Participants	20 Participants	18 Participants	9 Participants	56 Participants	70 Participants	98 Participants	35 Participants	36 Participants	40 Participants	57 Participants	19 Participants

PRIMARY outcome

Timeframe: Day 1 to Day 28

Population: The analysis was performed on the ES, which included all participants who received a study intervention and for whom unsolicited AEs data were available at specified timepoints.

An unsolicited AE is defined as an AE that was either not included in the list of solicited events or could be included in the list of solicited events but with an onset outside the specified period of follow up for solicited events. Unsolicited AEs include both serious and non-serious AEs. Any = occurrence the event regardless of intensity grade or relation to the study vaccination.

Outcome measures

Outcome measures
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group n=21 Participants YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group n=25 Participants YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group n=23 Participants YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group n=23 Participants YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group n=115 Participants YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group n=108 Participants YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group n=137 Participants YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group n=120 Participants YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group n=119 Participants OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group n=122 Participants OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group n=125 Participants OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group n=117 Participants OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Number of Participants Reporting Any Unsolicited AEs	7 Participants	10 Participants	5 Participants	7 Participants	6 Participants	12 Participants	4 Participants	6 Participants	12 Participants	8 Participants	7 Participants	9 Participants	7 Participants	34 Participants	40 Participants	60 Participants	45 Participants	24 Participants	22 Participants	28 Participants	20 Participants

PRIMARY outcome

Timeframe: Day 1 to Day 183

Population: The analysis was performed on the ES, which included all participants who received a study intervention and for whom SAEs data were available at specified timepoints.

An SAE is any untoward medical occurrence that results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect in the offspring of a study participant, is an abnormal pregnancy outcome, or is a suspected transmission of any infectious agent via an authorized medicinal product. Any = occurrence the event regardless of intensity grade or relation to the study vaccination.

Outcome measures

Outcome measures
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group n=21 Participants YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group n=25 Participants YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group n=23 Participants YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group n=23 Participants YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group n=115 Participants YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group n=108 Participants YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group n=137 Participants YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group n=120 Participants YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group n=119 Participants OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group n=122 Participants OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group n=125 Participants OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group n=117 Participants OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Number of Participants Reporting Serious Adverse Events (SAEs)	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants	0 Participants	0 Participants	1 Participants	0 Participants	3 Participants	3 Participants	6 Participants	2 Participants	2 Participants

PRIMARY outcome

Timeframe: Day 1 to Day 183

Population: The analysis was performed on the ES, which included all participants who received a study intervention and for whom AESI data were available at specified timepoints.

The following events were considered as AESI in this study: severe hypersensitivity reactions within 24 hours after study intervention administration, myocarditis/pericarditis and potential immune-mediated diseases (pIMDs). Any = occurrence the event regardless of intensity grade or relation to the study vaccination.

Outcome measures

Outcome measures
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group n=21 Participants YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group n=25 Participants YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group n=23 Participants YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group n=23 Participants YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group n=115 Participants YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group n=108 Participants YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group n=137 Participants YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group n=120 Participants YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group n=119 Participants OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group n=122 Participants OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group n=125 Participants OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group n=117 Participants OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Number of Participants Reporting AEs of Special Interest (AESIs)	1 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants	0 Participants	0 Participants	1 Participants	0 Participants	0 Participants	1 Participants	0 Participants

PRIMARY outcome

Timeframe: Day 1 to Day 183

Population: The analysis was performed on the ES, which included all participants who received a study intervention and for whom MAEs data were available at specified timepoints.

MAE is defined as an AE that results in an unscheduled visit to a medical professional (e.g., physician's office visits, emergency room visits or hospitalization). Any = occurrence the event regardless of intensity grade or relation to the study vaccination.

Outcome measures

Outcome measures
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group n=21 Participants YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group n=25 Participants YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group n=23 Participants YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group n=23 Participants YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group n=115 Participants YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group n=108 Participants YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group n=137 Participants YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group n=120 Participants YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group n=119 Participants OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group n=122 Participants OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group n=125 Participants OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group n=117 Participants OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Number of Participants Reporting Medically Attended Events (MAEs)	3 Participants	3 Participants	4 Participants	3 Participants	2 Participants	7 Participants	3 Participants	3 Participants	3 Participants	3 Participants	2 Participants	8 Participants	6 Participants	28 Participants	28 Participants	29 Participants	30 Participants	20 Participants	21 Participants	17 Participants	18 Participants

PRIMARY outcome

Timeframe: At Day 8 compared to baseline (Day 1)

Population: The analysis was performed on the ES, which included all participants who received a study intervention and for whom laboratory data were available at specified timepoints.

Outcome measures

Outcome measures
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group n=21 Participants YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group n=25 Participants YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group n=23 Participants YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group n=23 Participants YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Number of Participants Reporting a Shift From Abnormal Non-clinically Significant and Normal or Missing Laboratory Value on Day 1 to Clinically Significant Abnormal Laboratory Value on Day 8 for Hematology, and Clinical Chemistry Abnormal non-significant to clinically significant	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants	—	—	—	—	—	—	—	—
Number of Participants Reporting a Shift From Abnormal Non-clinically Significant and Normal or Missing Laboratory Value on Day 1 to Clinically Significant Abnormal Laboratory Value on Day 8 for Hematology, and Clinical Chemistry Normal or missing to clinically significant	0 Participants	1 Participants	0 Participants	1 Participants	0 Participants	2 Participants	0 Participants	1 Participants	2 Participants	1 Participants	0 Participants	0 Participants	1 Participants	—	—	—	—	—	—	—	—

PRIMARY outcome

Timeframe: At Day 29 compared to baseline (Day 1)

Population: The analysis was performed on the ES, which included all participants who received a study intervention and for whom laboratory data were available for the specified timepoints.

Outcome measures

Outcome measures
Measure	Flu mRNA_Ph1_1 Younger Adults (YA) Group n=20 Participants YA Participants received a single dose of Flu mRNA study intervention F2C22C/DL001Z (GSKVx000000039714) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_2 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22A/DL001Z (GSKVx000000040038) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_3 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2B22B/DL001Z (GSKVx000000040668) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_4 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2B22C/DL001Z (GSKVx000000040671) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_5 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2B22D/DL001Z (GSKVx000000040674) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_6 YA Group n=25 Participants YA participants received a single dose of Flu mRNA study intervention F2B22E/DL001Z (GSKVx000000040677) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_7 YA Group n=23 Participants YA participants received a single dose of Flu mRNA study intervention F2F22A/DL001Z (GSKVx000000040641) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_8 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22B/DL001Z (GSKVx000000040644) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_9 YA Group n=21 Participants YA participants received a single dose of Flu mRNA (GSK4382276A) study intervention F2F22C/DL001Z (GSKVx000000040647) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_10 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22D/DL001Z (GSKVx000000040650) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_11 YA Group n=22 Participants YA participants received a single dose of Flu mRNA study intervention F2F22E/DL001Z (GSKVx000000040996) administered in Phase 1, at Day 1.	Flu mRNA_Ph1_12 YA Group n=21 Participants YA participants received a single dose of Flu mRNA study intervention F2F22F/DL001Z (GSKVx000000040999) administered in Phase 1, at Day 1.	Control Ph1_YA Group n=22 Participants YA participants received a single dose of Control 1 administered in Phase 1, at Day 1.	Flu mRNA_Ph2_1_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23D/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1	Flu mRNA_Ph2_3_YA Group YA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_YA Group YA participants received single dose of Control 2 vaccine administered in Phase 2, at Day 1.	Flu mRNA_Ph2_1_Older Adults (OA) Group OA participants received a single dose of Flu mRNA study intervention F2F23A/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_2_OA Group OA participants received a single dose of Flu mRNA study intervention F2F23B/DL001Z-NH administered in Phase 2, at Day 1.	Flu mRNA_Ph2_3_OA Group OA participants received a single dose of Flu mRNA study intervention F2F23C/DL001Z-NH administered in Phase 2, at Day 1.	Control_Ph2_OA Group OA participants received a single dose of Control 3 vaccine administered in Phase 2, at Day 1.
Number of Participants Reporting a Shift From Abnormal Non-clinically Significant and Normal or Missing Laboratory Value on Day 1 to Clinically Significant Abnormal Laboratory Value on Day 29 for Hematology, and Clinical Chemistry Abnormal non-significant to clinically significant	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants	0 Participants	1 Participants	0 Participants	0 Participants	0 Participants	—	—	—	—	—	—	—	—
Number of Participants Reporting a Shift From Abnormal Non-clinically Significant and Normal or Missing Laboratory Value on Day 1 to Clinically Significant Abnormal Laboratory Value on Day 29 for Hematology, and Clinical Chemistry Normal or missing to clinically significant	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants	0 Participants	0 Participants	1 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	—	—	—	—	—	—	—	—

PRIMARY outcome

Timeframe: At Day 29

Population: The analysis was performed on the Per Protocol Set (PPS), which included all eligible participants who received the study intervention dose according to the protocol, had recorded anti-HI immunogenicity results pre- and post-dose, without intercurrent conditions, and did not use prohibited medications or vaccinations before Day 29 and for whom data were available for the specified analysis at the specified timepoints. Blood sample results that deviated from the analysis criteria were excluded.

Assay 1= with egg propagated Influenza virus and Assay 2= with cell propagated Influenza virus.