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INFLUENZA A VIRUS SUBTYPE H1N1 HAEMAGGLUTININ, RECOMBINANT

Clinical trials of INFLUENZA A VIRUS SUBTYPE H1N1 HAEMAGGLUTININ, RECOMBINANT are testing influenza vaccines in adults. They mainly look at immune response, safety, and how well the vaccine lots compare with each other or with other influenza vaccines. The studies include healthy adults and older adults, including people with stable health problems that raise influenza risk.

Table of contents

Overview of the trials

The clinical trials in this set study influenza vaccines that include INFLUENZA A VIRUS SUBTYPE H1N1 HAEMAGGLUTININ, RECOMBINANT as one of the vaccine components.[1][2][3] The main goals are to measure the immune response and to check safety after vaccination.[1][2] One Phase 3 study also looks at lot-to-lot consistency, which means whether different production lots of the same vaccine give similar immune responses.[3]

Who the studies include

Two Phase 2 studies include adults 18 years of age and older.[1][2] The Phase 3 study includes adults aged 50 years and older.[3] That Phase 3 trial includes both healthy people and people with stable comorbidities, which means ongoing health conditions that do not change quickly but may raise the risk of influenza complications.[3]

Trial phases and study design

The studies are interventional, which means participants receive a study vaccine or a comparison vaccine and researchers measure the results.[1][2][3] Two trials are in Phase 2 and one trial is in Phase 3.[1][2][3] The Phase 2 studies are focused on immune response and safety in adults, while the Phase 3 study tests larger-scale immunogenicity and comparison between vaccine lots and other influenza vaccines.[1][2][3]

What the trials measure

The Phase 2 studies measure antibody titer at Day 29, which is the amount of antibodies in the blood after vaccination.[1][2] They also measure the fold increase in antibody titer from Day 1 to Day 29, seroconversion from Day 1 to Day 29, and seroprotection at Day 1 and Day 29.[1][2] In addition, they track solicited administration site or systemic events within 7 days, unsolicited adverse events within 28 days, serious adverse events within 6 months, adverse events of special interest within 6 months, medically attended adverse events within 6 months, and laboratory abnormalities at several time points.[1][2]

The Phase 3 study measures immunogenicity using hemagglutination inhibition, or HI, assay results at Day 29.[3] It compares three lots of the same vaccine to see if they give similar results, and it also compares the vaccine with QIVr and aQIV for each strain in the vaccine.[3] The main immune measures are geometric mean titer, geometric mean titer ratio, seroconversion rate, and differences in seroconversion rate.[3]

Main studies in the data

Study 2025-522278-35-00 is a completed Phase 2 trial in 770 adults 18 years and older with influenza, human.[1] Its brief summary says it was designed to evaluate the humoral immune response, which means the antibody response in blood, and the safety and reactogenicity profile of the study interventions.[1] The primary outcomes focus on antibody response at Day 29 and safety events after vaccination.[1]

Study NCT07204964 is an authorised Phase 2 trial in 960 adults 18 years and older with influenza, human.[2] It uses the same main approach, looking at immune response and safety, with the same types of antibody and safety outcomes measured over time.[2]

Study 2023-503763-42-00 is a completed Phase 3 study in 6,300 adults aged 50 years and older.[3] It first tested lot-to-lot consistency of three vaccine lots and then tested immunological noninferiority, meaning whether the immune response was not worse than the comparison vaccines by more than a set amount.[3] The study compared aQIVc HD with QIVr and aQIV for each vaccine strain using HI assay results from cell-derived target viruses.[3]

Important terms explained

Humoral immune response means the part of the immune system that makes antibodies in the blood.[1][2] Seroconversion means a clear rise in antibodies after vaccination.[1][2] Seroprotection means an antibody level thought to give protection.[1][2]

Reactogenicity describes short-term reactions after vaccination, such as local or body-wide symptoms.[1][2] Adverse events are unwanted health problems that happen during a study, even if they are not caused by the vaccine.[1][2] Serious adverse events are more severe problems that may need urgent care or hospital treatment.[1][2]

Trial IDPhaseCondition studiedStatusEnrollment
2025-522278-35-00Phase 2Influenza, HumanCompleted770
NCT07204964Phase 2Influenza, HumanAuthorised960
2023-503763-42-00Phase 3Healthy individuals or individuals with stable comorbidities which increase their risk of complications from influenza infectionCompleted6300

FAQ

  • What are clinical trials with INFLUENZA A VIRUS SUBTYPE H1N1 HAEMAGGLUTININ, RECOMBINANT trying to find out? They are mainly checking if the vaccine helps the body make an immune response and whether it is safe. Some trials also compare different vaccine lots or compare this vaccine with other influenza vaccines.
  • Who can take part in these studies? The trials include adults 18 years and older, and one large study focuses on adults 50 years and older. Some older adults may have stable health problems that increase the risk of influenza complications.
  • What phase are these trials in? The studies are in Phase 2 and Phase 3. Phase 2 studies often look at immune response and safety, while Phase 3 studies usually test results in larger groups and compare vaccines more closely.
  • What outcomes are measured in the trials? The trials measure antibody levels, changes in antibody levels, seroconversion, and seroprotection. They also track side effects after vaccination, serious adverse events, and laboratory changes.
  • What conditions are being studied? The main condition is influenza, human. One study includes healthy people and people with stable comorbidities, which means other ongoing health problems that are not changing quickly.

Ongoing Clinical Trials on INFLUENZA A VIRUS SUBTYPE H1N1 HAEMAGGLUTININ, RECOMBINANT

  • Study of mRNA-based seasonal influenza vaccine to evaluate immune response and safety in adults 18 years and older

    Not recruiting

    1 1 1
    Investigated diseases:
    Investigated drugs:
    Belgium

  • Study of mRNA-based seasonal influenza vaccine combinations compared to standard influenza vaccines in adults aged 18 and older

    Not recruiting

    1 1 1
    Investigated diseases:
    Investigated drugs:
    Belgium

  • Study on the Safety and Immune Response of aQIVc HD Vaccine Compared to a Drug Combination for Adults 50 Years and Older at Risk of Flu Complications

    Not recruiting

    1 1 1 1
    Investigated diseases:
    Investigated drugs:
    Denmark Estonia Germany

Glossary

  • Influenza, Human: A viral infection of the respiratory system, often called the flu.
  • Interventional study: A trial where participants receive a study vaccine or comparison vaccine so researchers can measure the results.
  • Phase 2: An early-to-mid stage trial that usually looks at safety and immune response.
  • Phase 3: A larger trial stage that compares treatments or vaccines and confirms results in more people.
  • Immunogenicity: How well a vaccine makes the immune system respond.
  • Humoral immune response: The part of the immune response that uses antibodies in the blood.
  • Antibody titer: A measure of how much antibody is in the blood.
  • Seroconversion: A change showing that the body has started making a measurable antibody response.
  • Seroprotection: A blood level of antibodies thought to give protection.
  • Reactogenicity: Short-term reactions after a vaccine, such as local or general symptoms.
  • Adverse event: Any unwanted medical problem that happens during a study, whether or not it is caused by the vaccine.
  • Serious adverse event: A serious medical problem, such as one that needs hospital care or is life-threatening.

References

  1. https://clinicaltrials.gov/study/2025-522278-35-00
  2. https://clinicaltrials.eu/trial/study-of-mrna-based-seasonal-influenza-vaccine-to-evaluate-immune-response-and-safety-in-adults-18-years-and-older/
  3. https://clinicaltrials.gov/study/2023-503763-42-00