> Trialight public data. Index of pages: https://trialight.com/llms.txt > Web page: https://trialight.com/data/trial/safety-and-immunogenicity-of-different-formulations-of-an-d0bb175a-a50b-40d5-a81d-e01b2e4d7cf8 > Record changed: 2026-10-13 # Safety and Immunogenicity of Different Formulations of an MF59-Adjuvanted Influenza Vaccine in Older Adults ≥50 Years of Age NCT05501561 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) Phase Phase 2 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) Recruitment status Completed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) Participants 1,056 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) Lead sponsor Seqirus Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) Start date 2022-08-25 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) Number of sites 47 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) ## Title and summary **Summary** This Phase 2, randomized, observer-blind, dose-confirmation clinical study evaluated different formulations of MF59-Adjuvanted Quadrivalent Subunit Inactivated Influenza Vaccine. Approximately 1000 subjects were randomized into 1 of 4 possible treatment groups with approximately 250 participants per group. Every participant received an influenza vaccine injection on Day 1 and were to be followed up for approximately 6 months following injection. The primary immunogenicity analysis is based on Day 29 serology data. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Short title** Safety and Immunogenicity of Different Formulations of an MF59-Adjuvanted Influenza Vaccine in Older Adults ≥50 Years of Age Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Official title** A Phase 2b, Randomized, Observer-Blind, Antigen and Adjuvant Dose-Confirmation Clinical Study to Evaluate Safety and Immunogenicity of Different Formulations of MF59-Adjuvanted Quadrivalent Subunit Inactivated Cell-derived Influenza Vaccine (aQIVc) in Older Adults ≥50 Years of Age Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) ## Status and phase **Control arm** Active comparator Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Registry reports results** Yes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Listing at source** Listed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Recruitment status** Completed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Phase** Phase 2 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Study type** Interventional Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) ## Dates **Completion date** 2023-03-31 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **First posted** 2022-08-15 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Registry last updated** 2026-06-30 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Primary completion date** 2023-03-31 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Start date** 2022-08-25 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) ## Size and sites **Actual participants** 1,056 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Participants** 1,056 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Participant count basis** Actual Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Protocol amendments** 3 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Number of sites** 47 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) ## Sponsor and oversight **Data monitoring committee** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Registry sponsor category** Industry Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Lead sponsor** Seqirus Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Source registry** ClinicalTrials.gov Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) ## Identifiers **Registry ID** NCT05501561 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **ClinicalTrials.gov ID** NCT05501561 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) **Registry record** Open registry record Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) ## Study design **Allocation** Randomised **Model** Parallel groups **Purpose** Prevention **Masking** Quadruple masking **Masked roles** Participants, Care providers, Investigators, Outcome assessors Sources for study design Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT05501561) ## Outcomes ### Primary outcomes 1. Immunogenicity Endpoint: Geometric Mean Titer (GMT): Geometric Mean of Hemagglutination Inhibition (HI) Antibodies at Day 1 and Day 29 Timeframe: Day 1 and Day 29 GMTs on Day 1 (prior to vaccination) and Day 29 as determined by HI assay against each of the 4 vaccine strains. No hypothesis testing was performed for the primary immunogenicity objectives. 2. Immunogenicity Endpoint: Geometric Mean Fold Increase (GMFI) (HI Assay) Timeframe: Day 1 to Day 29 Geometric mean of the fold increase in serum HI titer postvaccination (Day 29) compared to prevaccination (Day 1) for each of the 4 vaccine strains. 3. Immunogenicity Endpoint: Percentages of Subjects With HI Titers ≥1:40 at Day 1 and Day 29 Timeframe: Day 1 and Day 29 Percentages of subjects with HI titers ≥1:40 at Day 1 and Day 29 for each of the 4 vaccine strains. 4. Immunogenicity Endpoint: Percentage of Subjects With Seroconversion at Day 29 (HI Assay) Timeframe: Day 1 to Day 29 Seroconversion is defined as ≥4-fold increase in titer postvaccination in those with prevaccination titer equal to or above the lower limit of quantitation (LLOQ; 1:10), or a postvaccination titer ≥1:40 for subjects with baseline titer below the LLOQ (1:10) for HI antibodies. 5. Immunogenicity Endpoint: GMT Ratio (HI Assay) Timeframe: Day 29 The GMT ratio is the geometric mean of the postvaccination HI titer for the investigational vaccine over the geometric mean of the postvaccination HI titer for the licensed IIV vaccine. The Day 29 GMT ratios are calculated for the investigational vaccines with reference to the licensed vaccine, ie, the Day 29 GMT ratios are the ratio of the Day 29 GMTs in the Investigational group (IIV-A Investigational, aIIV-B Investigational, or aIIV-C Investigational) compared with the Day 29 GMTs in the Licensed IIV group (ie, Investigational group/Licensed IIV group). As the licensed vaccine is the reference for the GMT ratio, this parameter is presented as "1" for the Licensed IIV group (ie, Licensed IIV group/Licensed IIV group). 6. Solicited Local or Systemic AEs Timeframe: Day 1 through Day 7 Number and percentage of subjects with solicited local or systemic AEs for 7 days following vaccination, based on the subject reported data (electronic Diary \\\[eDiary\\\]). No hypothesis testing was performed for the primary safety objectives. 7. Severe Solicited Local or Systemic AEs Timeframe: Day 1 through Day 7 Number and percentage of subjects with severe solicited local or systemic AEs for 7 days following vaccination, based on the subject reported data (eDiary). 8. Unsolicited AEs Timeframe: Day 1 to Day 29 Number and percentage of subjects with unsolicited AEs for 28 days following vaccination 9. Subjects With Serious Adverse Events (SAEs), AEs Leading to Withdrawal, Adverse Events of Special Interest (AESIs) and Medically-attended Adverse Events (MAAEs) Timeframe: Day 1 to Day 181 Number and percentage of subjects with SAEs, AEs leading to withdrawal from the study, AESIs and non-serious MAAEs ### Secondary outcomes 1. Immunogenicity Endpoint: GMT: Geometric Mean of Microneutralization (MN) Antibodies Titer at Days 1 and 29 Timeframe: Day 1 and Day 29 GMTs on Day 1 (prior to vaccination) and Day 29 as determined by MN assay against each of the 4 vaccine strains. 2. Immunogenicity Endpoint: GMFI (MN Assay) Timeframe: Day 1 to Day 29 Geometric mean of the fold increase in serum MN titer postvaccination (Day 29) compared to prevaccination (Day 1) for each of the 4 vaccine strains. 3. Immunogenicity Endpoint: Percentages of Subjects With Seroconversion at Day 29 (MN Assay) Timeframe: Day 1 to Day 29 Seroconversion is defined as ≥4-fold increase for subjects with prevaccination MN titers ≥LLOQ (1:10) or as ≥4\\\*LLOQ (1:10) for subjects with prevaccination MN titer \\