Trial Outcomes & Findings for Characterizing Late-season Influenza Vaccine Responses to Compare the 2023 and 2024 Vaccine Formulations (NCT NCT06567860)
NCT ID: NCT06567860
Last Updated: 2026-02-12
Results Overview
The antibody response will be measured by hemagglutination inhibition (HAI) in adults between 18 and 64 years old who have not had an influenza vaccination prior to the study.
Recruitment status
COMPLETED
Study phase
PHASE4
Target enrollment
23 participants
Primary outcome timeframe
0, 30, and 90 days after the 2023 vaccine
Results posted on
2026-02-12
Participant Flow
Participants were recruited into either Arm 1 (receiving only the late-season 2023 vaccine) or Arm 2 (receiving the late-season 2023 vaccine and then the 2024 vaccine three months later). 9 participants chose to participate in Arm 1 and 14 in Arm 2.
Participant milestones
| Measure |
Arm 1: Late-season 2023 Influenza Vaccine
Participants that had not been previously vaccinated for influenza during the 2023-24 season (i.e. no influenza vaccine since July 1, 2023) were given the 2023 vaccine in either May or June of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination.
|
Arm 2: Late-season 2023 Influenza Vaccine Followed by the 2024 Influenza Vaccine
As in Arm 1, participants that had not been previously vaccinated for influenza during the 2023-24 season were given the 2023 vaccine in either May or June of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination. Following that, participants were given the 2024 influenza vaccine in September, October, or November of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination.
|
|---|---|---|
|
Overall Study
STARTED
|
9
|
14
|
|
Overall Study
COMPLETED
|
9
|
14
|
|
Overall Study
NOT COMPLETED
|
0
|
0
|
Reasons for withdrawal
Withdrawal data not reported
Baseline Characteristics
Characterizing Late-season Influenza Vaccine Responses to Compare the 2023 and 2024 Vaccine Formulations
Baseline characteristics by cohort
| Measure |
Arm 1: Late-season 2023 Influenza Vaccine
n=9 Participants
Participants that had not been previously vaccinated for influenza during the 2023-24 season (i.e. no influenza vaccine since July 1, 2023) were given the 2023 vaccine in either May or June of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination.
|
Arm 2: Late-season 2023 Influenza Vaccine Followed by the 2024 Influenza Vaccine
n=14 Participants
As in Arm 1, participants that had not been previously vaccinated for influenza during the 2023-24 season were given the 2023 vaccine in either May or June of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination. Following that, participants were given the 2024 influenza vaccine in September, October, or November of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination.
|
Total
n=23 Participants
Total of all reporting groups
|
|---|---|---|---|
|
Age, Continuous
|
30 Years
STANDARD_DEVIATION 9 • n=41 Participants
|
28 Years
STANDARD_DEVIATION 5 • n=1581 Participants
|
29 Years
STANDARD_DEVIATION 7 • n=4626 Participants
|
|
Sex: Female, Male
Female
|
5 Participants
n=41 Participants
|
8 Participants
n=1581 Participants
|
13 Participants
n=4626 Participants
|
|
Sex: Female, Male
Male
|
4 Participants
n=41 Participants
|
6 Participants
n=1581 Participants
|
10 Participants
n=4626 Participants
|
|
Race (NIH/OMB)
American Indian or Alaska Native
|
0 Participants
n=41 Participants
|
0 Participants
n=1581 Participants
|
0 Participants
n=4626 Participants
|
|
Race (NIH/OMB)
Asian
|
0 Participants
n=41 Participants
|
3 Participants
n=1581 Participants
|
3 Participants
n=4626 Participants
|
|
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
|
0 Participants
n=41 Participants
|
0 Participants
n=1581 Participants
|
0 Participants
n=4626 Participants
|
|
Race (NIH/OMB)
Black or African American
|
0 Participants
n=41 Participants
|
0 Participants
n=1581 Participants
|
0 Participants
n=4626 Participants
|
|
Race (NIH/OMB)
White
|
5 Participants
n=41 Participants
|
6 Participants
n=1581 Participants
|
11 Participants
n=4626 Participants
|
|
Race (NIH/OMB)
More than one race
|
0 Participants
n=41 Participants
|
5 Participants
n=1581 Participants
|
5 Participants
n=4626 Participants
|
|
Race (NIH/OMB)
Unknown or Not Reported
|
4 Participants
n=41 Participants
|
0 Participants
n=1581 Participants
|
4 Participants
n=4626 Participants
|
|
Ethnicity (NIH/OMB)
Hispanic or Latino
|
6 Participants
n=41 Participants
|
3 Participants
n=1581 Participants
|
9 Participants
n=4626 Participants
|
|
Ethnicity (NIH/OMB)
Not Hispanic or Latino
|
3 Participants
n=41 Participants
|
10 Participants
n=1581 Participants
|
13 Participants
n=4626 Participants
|
|
Ethnicity (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=41 Participants
|
1 Participants
n=1581 Participants
|
1 Participants
n=4626 Participants
|
PRIMARY outcome
Timeframe: 0, 30, and 90 days after the 2023 vaccinePopulation: HAI titers were computed for all participants in each arm at every time point using the geometric mean and the geometric standard deviation, E\^(standard deviation of log(titers)). For example, the value of 6±1.4 for Arm 1's H1N1 day 0 measurement should be interpreted as a geometric mean of 6, and a 1.4x standard error (so that values were generally between 6/1.4 and 6×1.4).
The antibody response will be measured by hemagglutination inhibition (HAI) in adults between 18 and 64 years old who have not had an influenza vaccination prior to the study.
Outcome measures
| Measure |
Arm 1: Late-season 2023 Influenza Vaccine
n=9 Participants
Participants that had not been previously vaccinated for influenza during the 2023-24 season (i.e. no influenza vaccine since July 1, 2023) were given the 2023 vaccine in either May or June of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination.
|
Arm 2: Late-season 2023 Influenza Vaccine Followed by the 2024 Influenza Vaccine
n=14 Participants
As in Arm 1, participants that had not been previously vaccinated for influenza during the 2023-24 season were given the 2023 vaccine in either May or June of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination. Following that, participants were given the 2024 influenza vaccine in September, October, or November of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination.
|
|---|---|---|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
H1N1, Day 90
|
40 HAI Titer
Standard Deviation 5.1
|
21 HAI Titer
Standard Deviation 3.8
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
H3N2, Day 0
|
10 HAI Titer
Standard Deviation 2.8
|
9 HAI Titer
Standard Deviation 2.1
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
H3N2, Day 30
|
43 HAI Titer
Standard Deviation 5.2
|
42 HAI Titer
Standard Deviation 3.2
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
H3N2, Day 90
|
34 HAI Titer
Standard Deviation 5.4
|
28 HAI Titer
Standard Deviation 2.6
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
B Victoria, Day 0
|
8 HAI Titer
Standard Deviation 1.6
|
10 HAI Titer
Standard Deviation 1.9
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
B Victoria, Day 30
|
54 HAI Titer
Standard Deviation 2.5
|
57 HAI Titer
Standard Deviation 2.6
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
B Victoria, Day 90
|
34 HAI Titer
Standard Deviation 2.1
|
46 HAI Titer
Standard Deviation 2.7
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
B Yamagata, Day 0
|
47 HAI Titer
Standard Deviation 5.2
|
46 HAI Titer
Standard Deviation 4.0
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
B Yamagata, Day 30
|
254 HAI Titer
Standard Deviation 2.8
|
145 HAI Titer
Standard Deviation 3.2
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
B Yamagata, Day 90
|
148 HAI Titer
Standard Deviation 3.4
|
88 HAI Titer
Standard Deviation 3.0
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
H1N1, Day 30
|
74 HAI Titer
Standard Deviation 4.8
|
27 HAI Titer
Standard Deviation 4.1
|
|
Magnitude of Antibody Response After the Late-season 2023 Vaccine
H1N1, Day 0
|
6 HAI Titer
Standard Deviation 1.4
|
6 HAI Titer
Standard Deviation 1.5
|
PRIMARY outcome
Timeframe: Day 0, 30, and 90 after the 2024 vaccinePopulation: Serum was only collected for Arm 2 participants.
The antibody response will be measured by hemagglutination inhibition (HAI) in adults between 18 and 64 years old who have not had an influenza vaccination prior to the study. This outcome was only performed on Arm 2.
Outcome measures
| Measure |
Arm 1: Late-season 2023 Influenza Vaccine
Participants that had not been previously vaccinated for influenza during the 2023-24 season (i.e. no influenza vaccine since July 1, 2023) were given the 2023 vaccine in either May or June of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination.
|
Arm 2: Late-season 2023 Influenza Vaccine Followed by the 2024 Influenza Vaccine
n=14 Participants
As in Arm 1, participants that had not been previously vaccinated for influenza during the 2023-24 season were given the 2023 vaccine in either May or June of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination. Following that, participants were given the 2024 influenza vaccine in September, October, or November of 2024. Antibody HAI responses were measured 0, 30, and 90 days following this vaccination.
|
|---|---|---|
|
Magnitude of the Antibody Response After the 2024 Vaccine
H1N1, Day 0
|
—
|
16 HAI Titer
Standard Error 3.7
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
H1N1, Day 30
|
—
|
18 HAI Titer
Standard Error 3.6
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
H1N1, Day 90
|
—
|
16 HAI Titer
Standard Error 3.5
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
H3N2, Day 0
|
—
|
21 HAI Titer
Standard Error 3.0
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
H3N2, Day 30
|
—
|
31 HAI Titer
Standard Error 2.6
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
H3N2, Day 90
|
—
|
26 HAI Titer
Standard Error 2.8
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
B Victoria, Day 0
|
—
|
31 HAI Titer
Standard Error 2.7
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
B Victoria, Day 30
|
—
|
76 HAI Titer
Standard Error 2.3
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
B Victoria, Day 90
|
—
|
47 HAI Titer
Standard Error 2.1
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
B Yamagata, Day 0
|
—
|
80 HAI Titer
Standard Error 3.2
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
B Yamagata, Day 30
|
—
|
84 HAI Titer
Standard Error 3.6
|
|
Magnitude of the Antibody Response After the 2024 Vaccine
B Yamagata, Day 90
|
—
|
55 HAI Titer
Standard Error 3.2
|
Adverse Events
Arm 1: Late-season 2023 Influenza Vaccine
Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths
Arm 2: Late-season 2023 Influenza Vaccine Followed by the 2024 Influenza Vaccine
Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths
Serious adverse events
Adverse event data not reported
Other adverse events
Adverse event data not reported
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place