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Immunogenicity and safety of RSV A/B prefusion F protein vaccine versus RSV F glycoprotein recombinant adjuvanted vaccine in lung and stem cell transplant recipients

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

The study focuses on people who have received a lung transplant or an allogeneic haematopoietic stem cell transplant, groups that are at higher risk for severe illness from respiratory syncytial virus. Two different RSV vaccines are being tested: the powder called Abrysvo, which is mixed with a liquid and given as an injection into the muscle (intramuscular), and the suspension called Arexvy, which also contains an added ingredient (adjuvanted) to help the body’s immune system respond more strongly. Both vaccines aim to teach the immune system to recognize and fight the virus.

The purpose of the trial is to evaluate how well each vaccine stimulates an immune response, measured by the amount of specific antibodies produced one month after the vaccination series. Participants receive two doses of the assigned vaccine about a month apart, attend short clinic visits to provide blood and oral fluid samples, and are observed for any side effects for a week after each dose. Throughout the study, researchers also watch for any medically attended RSV infections and record any serious health events that occur.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline assessment

    Attend the first visit after joining the study. a small amount of blood is drawn and an oral fluid sample is collected to determine the initial level of antibodies against respiratory syncytial virus (rsv).

    Basic health information and current medications are recorded.

  2. Step 2

    First vaccine dose

    Receive a single injection of the assigned vaccine (abrysvo or arexvy). the dose is 0.5 ml given intramuscular (into a muscle).

    The injection is administered by a health professional in a clinical setting.

  3. Step 3

    Immediate post‑vaccination monitoring

    Remain in the clinic for a short observation period to ensure no immediate reaction occurs.

    Receive written instructions on how to record any side effects that appear during the next 7 days.

  4. Step 4

    Short‑term safety reporting

    For the 7 days after each injection, note any local symptoms (such as pain, redness or swelling at the injection site) and any systemic symptoms (such as fever, fatigue or headache).

    Report any symptoms that are moderate or severe, or any new medical problems, to the study team within 30 days after the injection.

  5. Step 5

    Second vaccine dose (arm B only)

    If assigned to the arexvy group, return for a second injection (visit 1b). the same dose—0.5 ml given intramuscular—is administered.

    The timing of this second dose follows the schedule defined by the study protocol.

  6. Step 6

    One‑month follow‑up (visit v2)

    Approximately one month after the final vaccine dose, attend a follow‑up visit.

    Blood is drawn again to measure the change in rsv‑specific antibodies. a rise of at least four‑fold compared with the baseline sample is considered a positive response.

    Additional safety information is collected, including any adverse events that occurred since the last visit.

  7. Step 7

    Long‑term follow‑up (visit v3)

    About one year after the first vaccine dose, return for the final study visit.

    Blood and oral fluid samples are collected to evaluate the durability of the antibody response.

    Any serious health events that occurred during the year, including hospitalizations or confirmed rsv infections, are recorded.

  8. Step 8

    Study completion

    After the final visit, no further study procedures are required.

    The study team will analyze the collected data to determine the safety and immune response of the vaccine strategies.

Who can join the trial?

5 criteria

  • Had a lung transplant (including combined transplants) at least 3 months before receiving the first vaccine dose.
  • Or had an allogeneic haematopoietic stem cell transplant (a transplant of blood‑forming stem cells from a donor) performed between 3 months and 5 years before the first vaccine dose.
  • Is currently in active follow‑up at one of the study centres, meaning your doctor is still regularly checking your health.
  • Is 18 years of age or older.
  • Can provide written informed consent, a signed form that shows you understand the study and agree to take part.

Who cannot join the trial?

19 criteria

  • Have received any RSV vaccine (licensed or experimental) before joining the study.
  • Are not covered by the French national health system (or an equivalent system).
  • Have a known allergy (hypersensitivity) that could be made worse by any ingredient in the vaccine.
  • Have an active cancer (malignant disease), except for non‑melanoma skin cancer.
  • Received immunoglobulins (antibody preparations) or any plasma derivatives within 90 days before the first vaccine dose, or plan to receive them during the study.
  • Had an acute cellular graft rejection treated with high‑dose steroids (corticosteroid boli) within one month before the first vaccine (applies to lung transplant recipients).
  • Are currently undergoing plasmapheresis (a procedure that filters blood) for acute antibody‑mediated graft rejection (applies to lung transplant recipients).
  • Have an ongoing acute graft‑versus‑host disease of grade II, III, or IV (a condition where donated immune cells attack the body) (applies to allogeneic haematopoietic stem cell transplant recipients).
  • Have chronic graft‑versus‑host disease that has not been stable for at least one month before the first vaccine (applies to allogeneic haematopoietic stem cell transplant recipients).
  • Received anti‑CD20 or anti‑CD52 therapy (medicines that target specific immune cells) within the last 6 months.
  • Received anti‑thymocyte globulin (a medication that suppresses the immune system) within the last 3 months.
  • Received any other vaccine within two weeks before joining the study, or plan to receive a vaccine within two weeks after each study vaccine dose.
  • Have a bleeding disorder that, in the investigator’s opinion, makes an intramuscular injection unsafe.
  • Are pregnant, breastfeeding (lactating), or planning to become pregnant during the study period (women of child‑bearing potential must have a negative pregnancy test and use effective contraception).
  • Are expected to be unavailable for the required study visits.
  • Are already participating in another active clinical trial that uses experimental medicines, vaccines, or invasive medical devices during the study period.
  • Have a severe feverish illness (febrile illness) at the time of enrollment.
  • Are detained or deprived of liberty by a judicial or administrative decision.
  • Are under legal protection measures (such as guardianship or other court‑ordered supervision).
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Investigated drugs

  • Abrysvo

    is a vaccine that protects against respiratory syncytial virus (RSV), a common virus that can cause serious lung infections. It contains two stabilized proteins from the two main groups of RSV, helping the body recognize and fight the virus. In this trial, the vaccine is given as a single injection into the muscle. Researchers are studying how well it triggers an immune response in patients who have had lung transplants or stem‑cell transplants.

  • Arexvy

    is another RSV vaccine that also aims to prevent severe RSV infection. It uses a specially designed RSV protein that is locked in a shape the immune system can easily recognize, and it includes an ingredient called AS01E that boosts the body’s response to the vaccine. Like Abrysvo, it is administered as a single intramuscular injection. The trial evaluates how strongly this vaccine stimulates antibodies in the same transplant patient groups.

What is already known about the treatment

  • Abrysvo

    This vaccine is given as a 0.5 ml intramuscular injection of a clear solution for injection. It is an approved recombinant RSV vaccine that contains two stabilized prefusion F proteins, one from RSV subgroup A and one from subgroup B, and is used to prevent respiratory syncytial virus infection in adults. The vaccine works by presenting the F protein to the immune system, prompting the body to make antibodies that block the virus from entering cells. It is classified as a viral subunit vaccine.

  • Arexvy

    This vaccine is administered as a 0.5 ml intramuscular injection of a suspension for injection. It is an approved recombinant RSV vaccine that contains a stabilized prefusion F protein combined with the AS01E adjuvant to boost the immune response. The F protein triggers the body to produce protective antibodies, while the adjuvant enhances the strength and duration of that response. It is also classified as a viral subunit vaccine.

Investigated diseases

  • Allogeneic Hematopoietic Stem Cell Transplant Recipient

    A person receives blood‑forming stem cells from a genetically different donor to replace their own marrow. After the transplant, the donor cells settle in the bone marrow and begin producing new blood cells, a process that can take several weeks to months. During this time, blood counts change as the new cells grow and mature. The immune system gradually re‑establishes, and the body may develop reactions against the donor cells, known as graft‑versus‑host disease, which can affect skin, liver, and gut. Over time the transplanted cells become the main source of blood and immune cells.

  • Lung Transplant Recipient

    A donor lung is surgically placed to replace a severely damaged or diseased lung. In the weeks following surgery, the transplanted lung starts to function and the body adapts to the new organ. The immune system may react to the donor tissue, leading to episodes of rejection that can affect breathing. Blood vessels and airways heal, and lung capacity typically improves as the organ integrates. The condition evolves as the transplanted lung stabilizes and the immune response is managed.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-524374-42-00Protocol code69HCL25_0854Estimated enrolment400 patientsSponsorHospices Civils De Lyon

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