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Study on Immune Responses to Avian Influenza Vaccine with A/Turkey/Turkey/1/05 (H5N1)-Like Strain in Patients with Avian and Seasonal Influenza

Registered 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 immune responses induced by vaccines for avian influenza and seasonal influenza. The study involves two vaccines: VaxigripTetra, which is a quadrivalent influenza vaccine designed to protect against four different flu viruses, and the Zoonotic Influenza Vaccine Seqirus, which targets the H5N1 strain of avian influenza. The purpose of the study is to evaluate how the body's immune system responds to these vaccines, particularly against the H5N1 2.3.4.4b clade of the avian influenza virus.

Participants in the study will receive the vaccines as injections. The VaxigripTetra vaccine is administered either into the muscle or under the skin, while the Zoonotic Influenza Vaccine Seqirus is given directly into the muscle. The study will monitor the immune response by measuring the levels of antibodies and specific immune cells in the blood. This will help determine how well the vaccines work in stimulating the body's defense mechanisms against the influenza viruses.

The study will take place over a period of time, with participants receiving doses of the vaccines and then having their immune responses checked at various intervals. The main focus is on the body's production of antibodies and the activation of immune cells that can fight off the influenza viruses. This research aims to provide valuable insights into the effectiveness of these vaccines in preventing influenza infections.

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, ensure that all eligibility criteria are met. This includes being between the ages of 18 and 65, planning to receive at least one dose of the avian influenza vaccine, and being able to provide samples at specified intervals.

    Written informed consent must be provided, and the ability to understand the given information is required. Participation is open to pregnant and lactating women.

  2. Step 2

    First vaccine dose

    Receive the first dose of the avian influenza vaccine. This vaccine is designed to protect against the H5N1 virus.

    The vaccine is administered as a suspension for injection, either intramuscularly or subcutaneously.

  3. Step 3

    Second vaccine dose

    The second dose of the vaccine is given at least 21 days after the first dose. This is to ensure the best possible immune response.

    The method of administration remains the same as the first dose.

  4. Step 4

    Sample collection

    Provide a blood sample 3 weeks after receiving the second vaccine dose. This sample is used to measure the immune response to the vaccine.

    The primary outcome is to assess the seroconversion proportion, which indicates the level of immune response developed.

  5. Step 5

    Follow-up visits

    Participate in follow-up visits at 6 and 12 months after the second vaccine dose. These visits help monitor the long-term immune response.

    Additional blood samples may be collected during these visits to further assess the immune response.

Who can join the trial?

8 criteria

  • Age between 18 to 65 years.
  • Belongs to the target group for the avian influenza vaccine.
  • Plans to receive at least one dose of the avian influenza vaccine.
  • Can understand the given written and spoken information.
  • Has given written consent to participate in the study.
  • Has a home address in Finland.
  • Can provide samples 3 weeks after each vaccine dose and preferably also participate in follow-ups at 6 and 12 months.
  • Pregnant and breastfeeding women can participate in the study.

Who cannot join the trial?

8 criteria

  • People who have had a severe allergic reaction to any ingredient in the vaccine cannot participate. A severe allergic reaction is when your body reacts very strongly to something, causing symptoms like trouble breathing or swelling.
  • Individuals with a history of Guillain-Barré syndrome cannot join. Guillain-Barré syndrome is a rare condition where the body's immune system attacks the nerves.
  • Anyone who is currently sick with a fever or an active infection should not participate until they are well. A fever is when your body temperature is higher than normal.
  • Pregnant women are not allowed to participate in the study.
  • People who have received another vaccine within the last 30 days cannot take part. This is to ensure that the effects of the study vaccine are not mixed with other vaccines.
  • Individuals who are taking medications that weaken the immune system are excluded. The immune system is the body's defense against infections and illnesses.
  • Anyone who has participated in another clinical trial within the last 30 days is not eligible. This is to avoid any interference with the results of this study.
  • People with a history of drug or alcohol abuse in the past year cannot participate. Abuse means using these substances in a way that is harmful to health.
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Investigated drugs

Avian Influenza Vaccine is a specially designed vaccine aimed at protecting against a specific type of bird flu, known as the H5N1 2.3.4.4b clade. This vaccine works by stimulating the body's immune system to recognize and fight off the virus if exposed in the future. The study is focused on understanding how well this vaccine can trigger both antibody responses and cell-based immune responses, which are crucial for effective protection against the virus.

What is already known about the treatment

Avian and seasonal influenza vaccine – This vaccine is administered through an injection to help protect against avian influenza, specifically the H5N1 2.3.4.4b clade, and seasonal influenza. Currently, it is being studied to understand how well it triggers the body's immune system, both in terms of antibody production and cellular response. The main therapeutic use of this vaccine is to prevent influenza infections caused by specific strains of the virus. It works by introducing a small, harmless part of the virus to the body, which helps the immune system recognize and fight the actual virus if exposed in the future. This vaccine falls under the pharmacological classification of vaccines, which are substances used to stimulate the production of antibodies and provide immunity against diseases.

Investigated diseases

  • Avian Influenza

    Avian influenza, also known as bird flu, is an infectious disease caused by influenza viruses that primarily affect birds but can also infect humans. The disease is characterized by symptoms such as fever, cough, sore throat, and muscle aches. In birds, it can cause a range of symptoms from mild illness to severe disease and death. In humans, the disease can progress rapidly, leading to respiratory distress and other complications. The virus spreads through direct contact with infected birds or contaminated environments. Human-to-human transmission is rare but can occur in certain conditions.

  • Seasonal Influenza

    Seasonal influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses that circulate worldwide. It typically presents with symptoms such as fever, cough, sore throat, body aches, and fatigue. The disease progresses over a few days, with symptoms usually resolving within a week, although some individuals may experience lingering fatigue. Influenza viruses are spread through respiratory droplets when an infected person coughs or sneezes. The virus can also be transmitted by touching surfaces contaminated with the virus and then touching the face. Seasonal influenza can lead to complications, especially in young children, the elderly, and individuals with weakened immune systems.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2023-509178-44-00Protocol codeAvian_inf_vacc_THL20Estimated enrolment300 patientsSponsorFinnish Institute For Health And Welfare

sourced from the EU Clinical Trials Register and site verification

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