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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

Fast replyRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial is focused on studying the effectiveness and safety of different types of vaccines for influenza, commonly known as the flu, in adults aged 50 years and older. The study involves a high-dose vaccine called aQIVc HD, which is a cell-derived vaccine enhanced with an ingredient called MF59 to boost the immune response. It is compared with two other vaccines: a non-enhanced vaccine called QIVr and another enhanced vaccine called aQIV, which is derived from eggs.

The purpose of the study is to evaluate how well these vaccines work in producing an immune response and how safe they are for the participants. The study will involve receiving one of the vaccines through an injection. Participants will be monitored for their immune response to the vaccine strains, which are specific types of the flu virus, and for any side effects. The study will last for about a year, with the main focus on the immune response measured at 29 days after vaccination.

Participants will include healthy individuals or those with stable health conditions that increase their risk of complications from the flu. The study aims to ensure that the high-dose vaccine is as effective and safe as the other vaccines. The vaccines are administered using a pre-filled syringe, which is a single-use device. The study will help determine the best vaccine option for older adults to protect them against the flu.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the study

    Upon joining the study, individuals aged 50 years and older, who are healthy or have stable conditions that increase their risk of complications from influenza, will be enrolled. Participants must be able to comply with all study procedures.

  2. Step 2

    Receiving the vaccine

    Participants will receive an injection of one of the following vaccines: aQIVc HD (high-dose MF59-adjuvanted quadrivalent subunit cell-derived influenza vaccine), QIVr (non-adjuvanted quadrivalent recombinant influenza vaccine), or aQIV (MF59-adjuvanted quadrivalent subunit egg-derived influenza vaccine).

    The vaccine is administered as a suspension for injection.

  3. Step 3

    Monitoring and follow-up

    Participants will be monitored for any immediate reactions from Day 1 to Day 7 for local and systemic reactions.

    Unsolicited adverse events will be recorded from Day 1 to Day 29.

    Serious adverse events, adverse events leading to withdrawal, adverse events of special interest, and medically attended adverse events will be monitored from Day 1 to Day 365.

  4. Step 4

    Immunogenicity assessment

    The study aims to evaluate the immune response to the vaccine by measuring antibody levels using a test called the hemagglutination inhibition (HI) assay.

    The primary assessment will occur on Day 29 to compare the immune response between different vaccine groups.

  5. Step 5

    Completion of the study

    The study is expected to conclude by June 28, 2025.

    Participants will have completed all required follow-ups and assessments by this date.

Who can join the trial?

4 criteria

  • Individuals aged 50 years and older.
  • Individuals who are healthy or have stable comorbidities. Comorbidities are other health conditions that a person might have. Stable means these conditions are not currently causing problems.
  • Individuals whose comorbidities increase their risk of complications from influenza infection. Influenza is commonly known as the flu.
  • Individuals who can comply with all study procedures. This means they can follow the instructions and attend all required appointments.

Who cannot join the trial?

4 criteria

  • Individuals who are not healthy or do not have stable comorbidities. Comorbidities are other health conditions that a person may have in addition to the main condition being studied.
  • Individuals who are not at increased risk of complications from influenza infection. Influenza is a viral infection that attacks your respiratory system.
  • Individuals who are younger than 50 years old.
  • Individuals who are part of a vulnerable population. This term refers to groups of people who may be at a higher risk of harm or exploitation.
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Investigated drugs

  • aQIVc HD

    is a high-dose influenza vaccine designed to protect against four different strains of the flu virus. It is made using a process that involves growing the virus in cells, which can help produce a strong immune response. This vaccine also includes an ingredient called an adjuvant, which helps boost the body's immune response to the vaccine, making it more effective, especially in older adults.

  • QIVr

    is a type of flu vaccine that also targets four different strains of the influenza virus. Unlike some other vaccines, it is made using recombinant technology, which means it is produced without using the actual flu virus. This method can be beneficial for people who have allergies to eggs, as it does not involve egg-based production. The vaccine is designed to help the immune system recognize and fight off the flu virus if exposed.

  • aQIV

    is another influenza vaccine that protects against four strains of the flu virus. It is made using a traditional method where the virus is grown in eggs. This vaccine also contains an adjuvant, which is an ingredient that enhances the immune response, making the vaccine more effective. It is particularly useful for older adults, who may need a stronger immune response to be protected against the flu.

What is already known about the treatment

aQIVc HD – This medication is a high-dose influenza vaccine administered via injection, designed to protect against the flu in adults aged 50 and older. It is currently being studied in clinical trials to ensure its effectiveness and safety compared to other flu vaccines. The main use of this vaccine is to prevent influenza, especially in healthy individuals or those with stable health conditions that increase their risk of flu complications. It works by stimulating the immune system to recognize and fight the flu virus, using a special ingredient called an adjuvant to boost the body's immune response. This vaccine is classified as an influenza vaccine, specifically designed to enhance protection in older adults.

Investigated diseases

Influenza – Influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses. It primarily affects the nose, throat, and sometimes the lungs. The disease typically begins suddenly and is characterized by symptoms such as fever, cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, and fatigue. Influenza can lead to mild to severe illness and can sometimes result in complications, especially in certain high-risk groups. The virus spreads mainly through droplets made when people with the flu cough, sneeze, or talk. It can also spread by touching surfaces or objects that have the virus on them and then touching the mouth, nose, or eyes.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-503763-42-00Protocol codeV201_03Estimated enrolment6 300 patientsSponsorSeqirus UK Limited

sourced from the EU Clinical Trials Register and site verification

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