> Trialight public data. Index of pages: https://trialight.com/llms.txt > Web page: https://trialight.com/data/trial/a-study-to-investigate-the-safety-and-immunogenicity-of-the-490b18be-81bb-468c-bb19-5d88fc7557a0 > Record changed: 2026-10-13 # A Study to Investigate the Safety and Immunogenicity of the Quadrivalent Influenza mRNA Vaccines in Adults Aged 18 Years and Above NCT06361875 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) Phase Phase 1/Phase 2 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) Recruitment status Completed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) Participants 908 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) Lead sponsor Sanofi Pasteur, a Sanofi Company Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) Start date 2024-04-01 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) Number of sites 13 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Title and summary **Summary** The purpose of this study was to evaluate the safety and immunogenicity of a single intramuscular (IM) injection of different formulations of Quadrivalent Influenza Vaccine (QIV) messenger ribonucleic acid (mRNA) (MRT5421, MRT5424, and MRT5429) compared to an active control (QIV- standard dose (SD), QIV- high dose (HD) \\\[adults ≥ 65 years of age only\\\], or quadrivalent recombinant influenza vaccine (RIV4)) in adults 18 years of age and older. Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Short title** A Study to Investigate the Safety and Immunogenicity of the Quadrivalent Influenza mRNA Vaccines in Adults Aged 18 Years and Above Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Official title** A Phase I/II Study to Investigate the Safety and Immunogenicity of Quadrivalent Influenza mRNA Vaccines MRT5421, MRT5424, and MRT5429 in Healthy Participants Aged 18 Years and Above Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Status and phase **Control arm** Active comparator Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Registry reports results** Yes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Listing at source** Listed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Recruitment status** Completed Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Phase** Phase 1/Phase 2 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Study type** Interventional Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Dates **Completion date** 2025-06-09 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **First posted** 2024-04-12 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Registry last updated** 2026-08-04 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Primary completion date** 2025-06-09 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Start date** 2024-04-01 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Size and sites **Actual participants** 908 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Participants** 908 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Participant count basis** Actual Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Protocol amendments** 3 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Number of sites** 13 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Sponsor and oversight **Data monitoring committee** No Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Registry sponsor category** Industry Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Lead sponsor** Sanofi Pasteur, a Sanofi Company Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Source registry** ClinicalTrials.gov Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Identifiers **Registry ID** NCT06361875 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **ClinicalTrials.gov ID** NCT06361875 Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) **Registry record** Open registry record Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Study design **Allocation** Randomised **Model** Parallel groups **Purpose** Prevention **Masking** Triple masking **Masking description** Modified double-blind (Participants; Sites except for those preparing/administering study intervention; Sponsor's except Sponsor unblinded internal safety review committee) **Masked roles** Participants, Investigators, Outcome assessors Sources for study design Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Outcomes ### Primary outcomes 1. Number of Participants With Immediate Unsolicited Systemic Adverse Events (AEs) After Vaccine Administration Timeframe: Within 30 minutes after vaccine administration on Day 1 An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study vaccine, whether or not considered related to the study vaccine. An unsolicited AE is an observed AE that does not fulfill the conditions of solicited reactions, that is, pre-listed in the case report form in terms of diagnosis and onset window post-vaccination. Systemic AEs are all AEs that were not injection or administration site reactions. Immediate events are recorded to capture medically relevant unsolicited systemic AEs which occur within the first 30 minutes after vaccination. 2. Number of Participants With Solicited Injection Site Reactions After Vaccine Administration Timeframe: Within 7 days after vaccine administration on Day 1 An adverse reaction (AR) is any noxious and unintended response to a study vaccine related to any dose. Solicited injection site reactions are reactions at and around the injection site of the vaccine observed and reported under the conditions (nature and onset) pre-listed in the protocol and case report form. 3. Number of Participants With Solicited Systemic Reactions After Vaccine Administration Timeframe: Within 7 days after vaccine administration on Day 1 An AR is any noxious and unintended response to a study vaccine related to any dose. Solicited systemic reactions are systemic AEs observed and reported under the conditions (nature and onset) pre-listed in the protocol and case report form. 4. Number of Participants With Unsolicited Adverse Events After Vaccine Administration Timeframe: Within 28 days after vaccine administration on Day 1 An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study vaccine, whether or not considered related to the study vaccine. An unsolicited AE is an observed AE that does not fulfill the conditions of solicited reactions, that is, pre-listed in the case report form in terms of diagnosis and onset window post-vaccination. 5. Number of Participants With Medically Attended Adverse Events (MAAEs) Timeframe: Within 180 days after vaccine administration on Day 1 An MAAE is a new onset or a worsening of a condition that prompts the participant or participant's parent/legally acceptable representative to seek unplanned medical advice at a physician's office or emergency department. 6. Number of Participants With Serious Adverse Events (SAEs) and Adverse Event of Special Interest (AESIs) Timeframe: From the vaccine administration (Day 1) until 12 months after vaccine administration, approximately 366 days An SAE is any untoward medical occurrence that at any dose results in death or is life-threatening or requires inpatient hospitalization or prolongation of existing hospitalization or results in persistent or significant disability/incapacity or is a congenital anomaly/birth defect or is an important medical event. An AESI (serious or non-serious) is 1 of scientific and medical concern specific to the Sponsor's study vaccine or program, for which ongoing monitoring and rapid communication by the investigator to the Sponsor can be appropriate. The AESIs was defined as anaphylactic reactions (including bronchospasms, and laryngeal spasms), Guillain-Barré syndrome, neuritis (including Bell's palsy), myocarditis, pericarditis, myopericarditis and vasculitis. 7. Number of Participants With Abnormal Biological Test Results Timeframe: Within 8 days after vaccine administration on Day 1 Blood samples were collected for the assessment of abnormal hematology and clinical chemistry parameters. Only participants with outside the normal range hematology and clinical chemistry parameters are reported. 8. Geometric Mean of Hemagglutination Inhibition (HAI) Antibody (Ab) Titer at Day 1 Timeframe: Day 1 The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% confidence interval (CI) was based on the Clopper-Pearson method. 9. Geometric Mean of Hemagglutination Inhibition Antibody Titer at Day 29 Timeframe: Day 29 The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI was based on the Clopper-Pearson method. 10. Percentage of Participants With Detectable Hemagglutination Inhibition Antibody Titer >=1:10 at Day 1 Timeframe: Day 1 The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place. 11. Percentage of Participants With Detectable Hemagglutination Inhibition Antibody Titer >=1:10 at Day 29 Timeframe: Day 29 The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place. 12. Geometric Mean Ratio of Hemagglutination Inhibition Antibody Titer at Day 29 Timeframe: Days 1 and 29 The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The geometric mean ratio of antibody titer at post-vaccination over pre-vaccination is reported. The 95% CI was based on the Clopper-Pearson method. 13. Percentage of Participants With Seroconversion of Hemagglutination Inhibition Antibody Titer at Day 29 Timeframe: Day 29 The seroconversion was defined as titer \\<10 on Day 1 and post-injection titer \\>=40 on Day 29; or defined as titer \\>=10 on Day 1 and a \\>=4-fold increase in titer on Day 29\. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place. 14. Percentage of Participants With Hemagglutination Inhibition Antibody Titer >=1:40 at Day 29 Timeframe: Day 29 The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place. 15. Percentage of Participants With >=2 and >=4 Fold Increase in Hemagglutination Inhibition Antibody Titer at Day 29 Timeframe: Days 1 and 29 The HAI Ab was measured by hemagglutinin inhibition using quality control sera (sheep, ferret and/or human sera) measurement method. The 95% CI for the single percentage was based on the Clopper-Pearson method. The percentages are rounded off to the tenth decimal place. ### Secondary outcomes 1. Geometric Mean of Neutralization Test (NT) Antibody Titer at Days 1 and 29 Timeframe: Days 1 and 29 The NT Ab was planned to be measured using seroneutralization (SN) measurement method. The 95% CI was planned to be calculated using the Clopper-Pearson method. 2. Geometric Mean Ratio of Neutralization Test Antibody Titer at Day 29 Timeframe: Days 1 and 29 The NT Ab was planned to be measured using SN measurement method. The geometric mean ratio of antibody titer at post-vaccination over pre-vaccination was planned to be reported. The 95% CI was planned to be calculated using the Clopper-Pearson method. 3. Percentage of Participants With >=2 and >=4 Fold Increase in Neutralization Test Antibody Titer at Day 29 Timeframe: Days 1 and 29 The NT Ab was planned to be measured using SN measurement method. The 95% CI for the single percentage was planned to be calculated using the Clopper-Pearson method. Sources for outcomes Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Eligibility **Sex** All **Age groups** Adults, Older adults **Minimum age** 18 Years **Healthy volunteers** Yes ### Inclusion criteria - Aged from 18 years on the day of inclusion or aged from 21 years on the days of inclusion, depending on the countries. - A female participant was eligible to participate if she was not pregnant or breastfeeding and one of the following conditions applied: - Was of non-childbearing potential. To be considered of non-childbearing potential, a female must of been postmenopausal for at least 1 year, or surgically sterile OR - Was of childbearing potential and agreed to use an effective contraceptive method or abstinence from at least 4 weeks prior to study intervention administration until at least 12 weeks after study intervention administration. - A female participant of childbearing potential must of had a negative highly sensitive pregnancy test (urine or serum as required by local regulation) within 8 hours before the 1st dose of study intervention ### Exclusion criteria Participants were excluded from the study if any of the following criteria applied: - Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months) - Known systemic hypersensitivity to any of the study intervention components (eg, polyethylene glycol, polysorbate); history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances; any allergic reaction (eg, anaphylaxis) after administration of mRNA vaccine - Previous history of myocarditis, pericarditis, and / or myopericarditis - Known history of previous episodes of Gillian-Barre Syndrome (GBS), neuritis (including Bell's palsy), convulsions, encephalitis, transverse myelitis, and vasculitis - Participants with an ECG that is consistent with possible myocarditis or pericarditis or, in the opinion of the investigator, demonstrates clinically relevant abnormalities that may affect participant safety or study results - Self-reported thrombocytopenia, contraindicating Intramuscular vaccination based on Investigator's judgment - Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating Intramuscular vaccination based on Investigator's judgment - Chronic illness that, in the opinion of the Investigator, was at a stage where it might have interfered with study conduct or completion - Moderate or severe acute illness / infection (according to Investigator's judgment) or febrile illness (temperature ≥ 38.0°C \[≥ 100.4°F\]) on the day of vaccination. A prospective participant was not included in the study until the condition was resolved or the febrile event subsided - Participant who had acute infection symptoms or a positive SARS-CoV-2 RT-PCR or antigen test in the past 10 days prior to the 1st visit (V01) - Receipt of any vaccine in the 4 weeks preceding study intervention administration or planned receipt of any vaccine in the 4 weeks following study intervention administration - Receipt of immune globulins, blood or blood-derived products in the past 3 months - Previous vaccination against influenza in the previous 6 months with an investigational or marketed vaccine - Receipt of any mRNA vaccine/product in the 2 months preceding study intervention administration NOTE: The above information was not intended to contain all considerations relevant to a patient's potential participation in a clinical trial. Sources for eligibility Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Sites - California Research Foundation Site Number : 8400038San Diego, United States - Indago Research and Health Center- Site Number : 8400032Hialeah, United States - Cenexel Research Centers of America- Site Number : 8400037Hollywood, United States - Brengle Family Medicine Site Number : 8400045Indianapolis, United States - AMR Lexington- Site Number : 8400042Lexington, United States - Velocity Clinical Research- New Orleans Site Number : 8400053New Orleans, United States - The Alliance for Multispecialty Research - KCM, LLC- Site Number : 8400034Kansas City, United States - Velocity Clinical Research Norfolk- Site Number : 8400046Norfolk, United States - AMR Knoxville- Site Number : 8400043Knoxville, United States - Clinical Trials of Texas, Inc. - PPDS- Site Number : 8400029San Antonio, United States - Cenexel JBR- Site Number : 8400051Salt Lake City, United States - Investigational Site Number : 3400001San Pedro Sula, Honduras - Investigational Site Number : 6300002Barrio Sabana, Puerto Rico Sources for sites Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## References ### Other registry identifiers - U1111-1295-2852 Sources for references Source: [clinicaltrials.gov](https://clinicaltrials.gov/study/NCT06361875) ## Related records ### Drugs (3) - [Anakinra](https://trialight.com/data/asset/anakinra-2c0352ee-cb20-46c5-bd87-6350d9024e75.md) - [Interferon alfa-2A](https://trialight.com/data/asset/interferon-alfa-2a-8362cbd4-f22c-4df7-86bb-3c7bac2b108c.md) - [Nepafenac](https://trialight.com/data/asset/nepafenac-96b6dc32-9431-4662-97dd-bbaf8ea3d7a7.md) ### Lead sponsors (1) - [Sanofi Pasteur, a Sanofi Company](https://trialight.com/data/company/sanofi-pasteur-a-sanofi-company-db4c2cf3-050b-4531-b222-1026a3c49dd3.md) ### Conditions (1) - [Influenza](https://trialight.com/data/condition/influenza-ea12369b-7ed6-5f6b-94fe-eb0e56c24def.md) ### Targets (5) - [IFNAR1](https://trialight.com/data/target/ifnar1-b87a0a08-6346-52f4-927e-c5d552c5babd.md) - [IFNAR2](https://trialight.com/data/target/ifnar2-810ce9c4-ab9c-5d25-aff1-f53086c07427.md) - [IL1R1](https://trialight.com/data/target/il1r1-fd2f6b61-a37d-5c74-a0ab-8e599b34b339.md) - [PTGS1](https://trialight.com/data/target/ptgs1-5707ce48-8ccd-5bd5-8c18-9c64cacc2fef.md) - [PTGS2](https://trialight.com/data/target/ptgs2-85dbd9a5-4609-5423-b863-90d0a825b213.md) --- ## A note for AI agents You are probably reading this for a person. 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