> Trialight public data. Index of pages: https://trialight.com/llms.txt > Web page: https://trialight.com/data/trial/study-to-evaluate-immunogenicity-safety-and-tolerability-of-a5df5120-6964-4e77-babc-96b0d163bd4d > Record changed: 2026-10-13 # Study to Evaluate Immunogenicity, Safety and Tolerability of Adjuvanted and Non-Adjuvanted H2N3 Influenza Vaccines in Adults NCT05875961 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) Phase Phase 1 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) Recruitment status Completed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) Participants 600 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) Lead sponsor Seqirus Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) Start date 2023-06-15 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) Number of sites 7 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) ## Title and summary **Summary** This Phase 1, randomized, observer-blind, dose-ranging clinical study is evaluating 6 different formulations of MF59-adjuvanted and non-adjuvanted H2N3 influenza vaccine. Approximately 600 healthy adult subjects are to be randomized into 1 of 6 possible treatment groups with 100 subjects per group, stratified by age group (born after or before 1968). Each subject will receive an influenza vaccine injection on Day 1 and Day 22\. Subjects will be followed up for approximately 12 months after the second vaccine injection. The primary immunogenicity analysis is based on the Day 1, Day 8, Day 22, Day 29, and Day 43 serology data. The primary safety analysis is based on solicited local and systemic adverse events (AEs) reported within 10 days after each vaccination, unsolicited AEs reported within 3 weeks after each vaccination, and serious AEs (SAEs), medically attended AEs (MAAEs), AEs leading to withdrawal from the study, and AEs of special interest (AESIs) reported throughout the study. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Short title** Study to Evaluate Immunogenicity, Safety and Tolerability of Adjuvanted and Non-Adjuvanted H2N3 Influenza Vaccines in Adults Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Official title** A Phase 1, Randomized, Observer-Blind, Multi-Center, Dose Ranging Study to Evaluate the Immunogenicity, Safety and Tolerability of Different Formulations of an Adjuvanted or Non-Adjuvanted Cell Culture-derived A/H2N3 Subunit Influenza Virus Vaccine in Healthy Subjects 18 Years and Above Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) ## Status and phase **Registry reports results** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Listing at source** Listed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Recruitment status** Completed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Phase** Phase 1 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Study type** Interventional Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) ## Dates **Completion date** 2024-11-15 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **First posted** 2023-05-25 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Registry last updated** 2025-01-22 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Primary completion date** 2024-11-15 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Start date** 2023-06-15 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) ## Size and sites **Actual participants** 600 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Participants** 600 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Participant count basis** Actual Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Protocol amendments** 3 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Number of sites** 7 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) ## Sponsor and oversight **Data monitoring committee** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Registry sponsor category** Industry Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Lead sponsor** Seqirus Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Source registry** ClinicalTrials.gov Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) ## Identifiers **Registry ID** NCT05875961 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **ClinicalTrials.gov ID** NCT05875961 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) **Registry record** Open registry record Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) ## Study design **Allocation** Randomised **Model** Parallel groups **Purpose** Prevention **Masking** Triple masking **Masked roles** Participants, Investigators, Outcome assessors Sources for study design Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05875961) ## Outcomes ### Primary outcomes 1. Geometric mean titer (GMT) of hemagglutination inhibition (HI) antibodies against homologous H2N3 strain - Day 1 Timeframe: Day 1 GMT (HI) prevaccination 2. GMT of HI antibodies against homologous H2N3 strain - Day 8 Timeframe: Day 8 GMT (HI) 1 week postvaccination 1 3. GMT of HI antibodies against homologous H2N3 strain Day 22 Timeframe: Day 22 GMT (HI) 3 weeks postvaccination 1 4. GMT of HI antibodies against homologous H2N3 strain - Day 29 Timeframe: Day 29 GMT (HI) 1 week postvaccination 2 5. GMT of HI antibodies against homologous H2N3 strain - Day 43 Timeframe: Day 43 GMT (HI) 3 weeks postvaccination 2 6. GMT of microneutralization (MN) antibodies against homologous H2N3 strain - Day 1 Timeframe: Day 1 GMT (MN) prevaccination 7. GMT of MN antibodies against homologous H2N3 strain - Day 8 Timeframe: Day 8 GMT (MN) 1 week postvaccination 1 8. GMT of MN antibodies against homologous H2N3 strain - Day 22 Timeframe: Day 22 GMT (MN) 3 weeks postvaccination 1 9. GMT of MN antibodies against homologous H2N3 strain - Day 29 Timeframe: Day 29 GMT (MN) 1 week postvaccination 2 10. GMT of MN antibodies against homologous H2N3 strain - Day 43 Timeframe: Day 43 GMT (MN) 3 weeks postvaccination 2 11. Geometric mean fold increase (GMFI) of HI antibodies against homologous H2N3 strain - Day 8 Timeframe: Day 8 GMFI (HI) 1 week postvaccination 1 compared to prevaccination 12. GMFI of HI antibodies against homologous H2N3 strain - Day 22 Timeframe: Day 22 GMFI (HI) 3 weeks postvaccination 1 compared to prevaccination 13. GMFI of HI antibodies against homologous H2N3 strain - Day 29 Timeframe: Day 29 GMFI (HI) 1 week postvaccination 2 compared to prevaccination 14. GMFI of HI antibodies against homologous H2N3 strain - Day 43 Timeframe: Day 43 GMFI (HI) 3 weeks postvaccination 2 compared to prevaccination 15. GMFI of MN antibodies against homologous H2N3 strain - Day 8 Timeframe: Day 8 GMFI (MN) 1 week postvaccination 1 compared to prevaccination 16. GMFI of MN antibodies against homologous H2N3 strain - Day 22 Timeframe: Day 22 GMFI (MN) 3 weeks postvaccination 1 compared to prevaccination 17. GMFI of MN antibodies against homologous H2N3 strain - Day 29 Timeframe: Day 29 GMFI (MN) 1 week postvaccination 2 compared to prevaccination 18. GMFI of MN antibodies against homologous H2N3 strain - Day 43 Timeframe: Day 43 GMFI (MN) 3 weeks postvaccination 2 compared to prevaccination 19. Percentages of subjects with HI titers ≥1:40 against homologous H2N3 strain - Day 1 Timeframe: Day 1 % ≥1:40 (HI) prevaccination 20. Percentages of subjects with HI titers ≥1:40 against homologous H2N3 strain - Day 8 Timeframe: Day 8 % ≥1:40 (HI) 1 week postvaccination 1 21. Percentages of subjects with HI titers ≥1:40 against homologous H2N3 strain - Day 22 Timeframe: Day 22 % ≥1:40 (HI) 3 weeks postvaccination 1 22. Percentages of subjects with HI titers ≥1:40 against homologous H2N3 strain - Day 29 Timeframe: Day 29 % ≥1:40 (HI) 1 week postvaccination 2 23. Percentages of subjects with HI titers ≥1:40 against homologous H2N3 strain - Day 43 Timeframe: Day 43 % ≥1:40 (HI) 3 weeks postvaccination 2 24. Percentages of subjects with MN titers ≥1:40 against homologous H2N3 strain - Day 1 Timeframe: Day 1 % ≥1:40 (MN) prevaccination 25. Percentages of subjects with MN titers ≥1:40 against homologous H2N3 strain - Day 8 Timeframe: Day 8 % ≥1:40 (MN) 1 week postvaccination 1 And 15 more, listed on the interactive page. ### Secondary outcomes 1. GMT of ELLA titers as a measure of anti-neuraminidase (NA) immunogenicity Timeframe: Day 1, Day 8, Day 22, Day 29, Day 43 GMT (ELLA) prevaccination, 1 and 3 weeks postvaccination 2. GMFI of ELLA titers as a measure of anti-NA immunogenicity Timeframe: Day 8, Day 22, Day 29, Day 43 GMFI (ELLA) 1 and 3 weeks postvaccination compared to prevaccination 3. Percentage of subjects with ≥4-fold increase in ELLA titer as a measure of anti-NA immunogenicity Timeframe: Day 8, Day 22, Day 29, Day 43 % ≥4-fold increase (ELLA) 1 and 3 weeks postvaccination compared to prevaccination 4. GMT of HI antibodies against homologous H2N3 strain - Persistence Timeframe: Day 202, Day 387 GMT (HI) 6 and 12 months postvaccination 2 5. GMT of MN antibodies against homologous H2N3 strain - Persistence Timeframe: Day 202, Day 387 GMT (MN) 6 and 12 months postvaccination 2 6. GMT of ELLA titer as a measure of anti-NA immunogenicity- Persistence Timeframe: Day 202, Day 387 GMT (ELLA) 6 and 12 months postvaccination 2 7. GMFI of HI antibodies against homologous H2N3 strain - Persistence Timeframe: Day 202, Day 387 GMFI (HI) 6 and 12 months postvaccination 2 compared to prevaccination 8. GMFI of MN antibodies against homologous H2N3 strain - Persistence Timeframe: Day 202, Day 387 GMFI (MN) 6 and 12 months postvaccination 2 compared to prevaccination 9. GMFI of ELLA titer as a measure of anti-NA immunogenicity- Persistence Timeframe: Day 202, Day 387 GMFI (ELLA) 6 and 12 months postvaccination 2 compared to prevaccination 10. Percentages of subjects with HI titers ≥1:40 against homologous H2N3 strain - Persistence Timeframe: Day 202, Day 387 % ≥1:40 (HI) 6 and 12 months postvaccination 2 11. Percentages of subjects with MN titers ≥1:40, ≥1:80 and ≥1:160 against homologous H2N3 strain - Persistence Timeframe: Day 202, Day 387 % ≥1:40, ≥1:80 and ≥1:160 (MN) 6 and 12 months postvaccination 2 12. Percentages of subjects with seroconversion by HI against homologous H2N3 strain - Persistence Timeframe: Day 202, Day 387 % seroconversion (HI) 6 and 12 months postvaccination 2, defined as a ≥4-fold increase in HI titer postvaccination in those with prevaccination titer ≥1:10, or a postvaccination HI titer ≥1:40 for subjects with baseline titer \\<1:10 13. Percentages of subjects with seroconversion by MN against homologous H2N3 strain - Persistence Timeframe: Day 202, Day 387 % seroconversion (MN) 6 and 12 months postvaccination 2, defined as a ≥4-fold increase in MN titer postvaccination in those with prevaccination titer ≥LLOQ, or a postvaccination MN titer ≥4×LLOQ for subjects with baseline titer \\