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Study on the Effectiveness and Safety of Chikungunya Vaccine (VLA-1553) for People at Risk of Severe Chikungunya in La Réunion

Verified siteRegistered 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, safety, and immune response of a vaccine for Chikungunya, an infectious disease caused by the chikungunya virus. The vaccine being tested is called IXCHIQ, which is a live attenuated vaccine, meaning it contains a weakened form of the virus to help the body build immunity without causing the disease. The vaccine is administered as a solution for injection.

The purpose of the study is to evaluate how well the chikungunya vaccine works in preventing the disease in people who are at risk of severe or complicated forms of chikungunya. Participants in the study will receive the vaccine and will be monitored over a period of time to see if they develop chikungunya. The study will also look at the rate of hospitalizations and any complications that may arise, such as joint pain or chronic symptoms like fatigue or anxiety.

The study will follow participants for up to 12 months, with an interim analysis at 3 months. This means that researchers will check in with participants at different points to see how they are doing and to gather information on the vaccine's effectiveness and safety. The goal is to understand how well the vaccine protects against chikungunya and to ensure it is safe for use in people who are more vulnerable to the disease.

The research process

The trial runs in 4 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 sign an informed consent form. This form confirms your understanding of the study and your agreement to participate.

    You must be eligible for the anti-chikungunya vaccination according to the health authority's recommendations and be a beneficiary of social security coverage.

    Participation is open to adults aged 18 years and older.

  2. Step 2

    Vaccination

    You will receive the chikungunya vaccine, which is a live vaccine administered as a solution for injection.

    The vaccine is given through an intramuscular injection. This means it is injected into a muscle, typically in the upper arm.

  3. Step 3

    Follow-up period

    After receiving the vaccine, you will enter a follow-up period to monitor the vaccine's effectiveness and safety.

    The primary goal is to measure the vaccine's effectiveness at 6 months by observing the occurrence of confirmed chikungunya cases.

    Interim analysis will occur at 3 months, and the full follow-up will conclude at 12 months from the date of vaccination.

  4. Step 4

    Monitoring and assessments

    Throughout the study, you will be monitored for any hospitalizations lasting over 24 hours and any serious complications.

    The study will also assess the rate of intensive care unit (ICU) hospitalizations or deaths, as well as any disabling complications such as joint pain or chronic conditions like fatigue or anxiety-depression.

    These assessments will occur at 3 months and at the end of the study.

Who can join the trial?

4 criteria

  • Sign the informed consent form. This means you agree to participate in the study after being told all the important details.
  • Be eligible for the anti-chikungunya vaccination according to the recommendations of the health authorities.
  • Have social security coverage. This means you are part of a health insurance system.
  • Agree to participate in the study if you are an adult, which means you are 18 years or older.

Who cannot join the trial?

3 criteria

  • Participants who have been previously vaccinated against chikungunya cannot join the study.
  • Individuals who have a confirmed chikungunya infection, identified by specific tests (PCR+ or IgM+), are not eligible.
  • People who are not part of the vulnerable population group are excluded.
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Investigated drugs

The clinical trial is focused on evaluating the effectiveness of a vaccine against chikungunya. The vaccine is designed to protect people from getting sick with chikungunya, a virus that can cause fever and joint pain. This vaccine works by helping the body’s immune system recognize and fight the chikungunya virus if the person is exposed to it in the future. The trial aims to see how well the vaccine works in preventing the disease, especially in people who are at higher risk of severe illness.

What is already known about the treatment

Chikungunya Vaccine – This vaccine is administered through an injection to help protect against the chikungunya virus, which is an infectious disease. Currently, it is being studied in a clinical trial to assess its effectiveness, safety, and ability to trigger an immune response in people at risk of severe or complicated forms of the disease. The main purpose of the vaccine is to prevent chikungunya infection, especially in vulnerable populations. It works by stimulating the body's immune system to recognize and fight the chikungunya virus if exposed. This vaccine falls under the category of immunizations designed to prevent viral infections.

Investigated diseases

Chikungunya – Chikungunya is a viral disease transmitted to humans by infected mosquitoes. It is characterized by the sudden onset of fever, joint pain, muscle pain, headache, nausea, fatigue, and rash. The joint pain is often very debilitating but usually lasts for a few days or may be prolonged to weeks. Most patients recover fully, but in some cases, joint pain may persist for several months or even years. The disease shares some clinical signs with dengue and Zika, and can be misdiagnosed in areas where these are common. The name "chikungunya" derives from a word in the Kimakonde language, meaning "to become contorted," and describes the stooped appearance of sufferers with joint pain.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2025-521307-43-00Estimated enrolment1 800 patientsSponsorCentre Hospitalier Universitaire De La Reunion

sourced from the EU Clinical Trials Register and site verification

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