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Study on Immune Responses to Influenza Vaccines in Health Care Workers Using Polysorbate 80, Sodium Citrate, and Citric Acid Anhydrous

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 to influenza vaccinations and viruses among healthcare personnel. Influenza, commonly known as the flu, is a contagious respiratory illness caused by influenza viruses. The study will use a vaccine that contains inactivated, split virus or surface antigen components, which include strains like A/Texas/50/2012 (H3N2) and A/California/7/2009 (H1N1). These components are designed to help the body build immunity against the flu.

The purpose of the study is to assess the presence and level of antibodies, which are proteins in the blood that fight infections, against the circulating influenza virus strains and the vaccine strains of the current season. Participants will receive the vaccine through an injection into the muscle. Blood samples will be taken before and after vaccination to measure the immune response. The study will also look at cellular immunity, which involves the body's cells responding to the virus, and will measure substances like cytokines, which are proteins that help control the immune response.

The study will take place over several years, with the goal of understanding how well the vaccine works in healthcare workers who are regularly exposed to the flu. This information could help improve future flu vaccines and protect people from getting sick. Participants will be monitored throughout the study to ensure their safety and to gather important data on how their bodies respond to the vaccine.

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, you will be required to provide written informed consent. This means you agree to participate after understanding the study's purpose and procedures.

    You must be between 18 and 64 years old, work as health care or laboratory personnel, and be in general good health.

  2. Step 2

    Vaccination

    You will receive a seasonal influenza vaccination as part of your routine occupational health care service. The vaccine is administered intramuscularly, which means it is injected into a muscle.

    The vaccine contains inactivated parts of the influenza virus, which help your body build immunity against the flu.

  3. Step 3

    Blood sample collection

    Before and after the vaccination, blood samples will be collected. These samples are used to measure the presence and level of antibodies against the influenza virus.

    The primary goal is to assess your body's humoral immunity, which involves antibodies that circulate in your blood.

  4. Step 4

    Assessment of cellular immunity

    Your cellular immunity will be evaluated using specific tests on your blood samples. This involves examining how your immune cells respond to the influenza virus.

    The study will measure the response of certain proteins, called cytokines, which are important for immune responses.

  5. Step 5

    Follow-up and monitoring

    Throughout the study, your health and immune responses will be monitored. This includes regular check-ins and possibly additional blood sample collections.

    The study is expected to continue until October 31, 2027, but your participation may not last the entire duration.

Who can join the trial?

5 criteria

  • Must be a male or female aged between 18 to 64 years.
  • Must be a member of health care or laboratory personnel who has decided to take the seasonal influenza vaccination through routine occupational health care services.
  • Must be in general good health as confirmed by the individual's own statement.
  • Must provide written informed consent, which means agreeing to participate in the study after understanding all the details.
  • Must be able and willing to participate in the study during the upcoming influenza season.

Who cannot join the trial?

7 criteria

  • People who are not within the age range specified for the study cannot participate.
  • Individuals who have a known allergy to any component of the vaccine will be excluded.
  • Participants who have received another vaccine within a certain period before the study starts may not be eligible.
  • Anyone with a serious illness or medical condition that could interfere with the study results will not be allowed to join.
  • Pregnant or breastfeeding women are not eligible to participate.
  • Individuals who are unable to comply with the study procedures or follow-up visits will be excluded.
  • People who have participated in another clinical trial recently may not be eligible.
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Investigated drugs

Influenza Vaccine is a type of vaccine designed to protect against the influenza virus, commonly known as the flu. The vaccine works by stimulating the body's immune system to produce antibodies against the virus, which can help prevent infection or reduce the severity of the illness if you do get sick. In this trial, the vaccine is used to study how well it triggers an immune response in health care personnel, both before and after they receive the vaccine.

What is already known about the treatment

Influenza Vaccine – The influenza vaccine is administered through an injection, typically into the muscle of the upper arm. It is widely used and well-documented in medical literature as a preventive measure against influenza, commonly known as the flu. The main purpose of the vaccine is to boost immunity and protect against the flu by stimulating the body's immune system to produce antibodies. These antibodies help recognize and fight off the influenza virus if exposed. The vaccine is classified as an immunization agent and is recommended annually to match circulating virus strains.

Investigated diseases

Influenza – Influenza is a contagious respiratory illness caused by influenza viruses. It primarily affects the nose, throat, and lungs. The disease typically begins suddenly with symptoms such as fever, cough, sore throat, muscle aches, and fatigue. As it progresses, individuals may experience headaches, chills, and a runny or stuffy nose. Influenza can lead to complications, especially in young children, elderly individuals, and those with weakened immune systems. The virus spreads through droplets when an infected person coughs, sneezes, or talks.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2024-515372-12-00Estimated enrolment1 500 patientsSponsorFinnish Institute For Health And Welfare

sourced from the EU Clinical Trials Register and site verification

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