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Study on the Safety and Immune Response of PHH-1V81 Booster for Adults Vaccinated Against COVID-19

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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 effects of a booster vaccination for COVID-19, a disease caused by the SARS-CoV-2 virus. The study involves two different vaccines. One is called Comirnaty Omicron XBB.1.5, which is a type of mRNA vaccine designed to protect against the Omicron variant of the virus. The other vaccine being studied is a new candidate called PHH-1V81, which is a recombinant protein vaccine. This means it uses a piece of the virus's protein to help the body recognize and fight the virus.

The purpose of the study is to assess the safety and immune response of the PHH-1V81 booster in adults who have already received their initial COVID-19 vaccinations and at least one booster dose of an mRNA vaccine approved in the European Union. Participants will receive either the PHH-1V81 booster or the Comirnaty Omicron XBB.1.5 vaccine. The study will compare how well each vaccine works in boosting the immune system's ability to fight the virus, particularly against the Omicron XBB.1.16 variant.

Throughout the study, participants will be monitored for any reactions or side effects after receiving the booster. The study will also measure the level of antibodies, which are proteins the body makes to fight infections, to see how well the vaccines work. The trial will help determine if the new PHH-1V81 vaccine is as effective as the existing Comirnaty vaccine in boosting immunity against COVID-19.

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

    Initial screening

    Upon joining the study, you will undergo an initial screening process. This includes a review of your medical history and a clinical assessment to ensure eligibility. A rapid antigen test for COVID-19 will be conducted to confirm a negative result before proceeding.

    If you are biologically able to become pregnant, a urine pregnancy test will be performed. You must have practiced adequate contraception or abstained from activities that could result in pregnancy for at least 28 days prior to the study treatment.

  2. Step 2

    Vaccination day

    On the day of vaccination, you will receive a booster dose of the PHH-1V81 vaccine or the Comirnaty Omicron XBB.1.5 vaccine. The vaccine is administered as an injection into the muscle (intramuscular).

    You will be monitored for any immediate reactions following the vaccination.

  3. Step 3

    Post-vaccination monitoring

    For the first 7 days after vaccination, you will be asked to report any local or systemic reactions. This includes any redness, swelling, or pain at the injection site, as well as any general symptoms like fever or fatigue.

    You will continue to report any adverse events for 28 days after vaccination. This includes any unexpected symptoms or medical issues that arise.

  4. Step 4

    Follow-up visits

    You will have follow-up visits scheduled at specific intervals: Day 14, Day 91, and Day 182. During these visits, blood samples may be taken to measure your immune response to the vaccine.

    The study will assess the level of antibodies in your blood and how well your body is responding to the vaccine over time.

  5. Step 5

    End of study

    The study is expected to conclude by June 30, 2024. You will be informed of the study's findings and any relevant information regarding your health and the vaccine's effectiveness.

    Throughout the study, you are encouraged to maintain communication with the study team regarding any health changes or concerns.

Who can join the trial?

14 criteria

  • Adults aged 18 or older at the start of the study.
  • Willing and able to sign a consent form and attend all study visits and procedures.
  • Must have received a primary series of an EU-approved mRNA vaccine (2 doses) and at least one booster dose with an EU-approved mRNA vaccine. The last booster dose must have been given at least 6 months before the start of the study.
  • Must have a negative Rapid Antigen Test for COVID-19 on the day of vaccination.
  • Adults with stable and well-controlled chronic diseases (not affecting the immune system) can participate if deemed eligible by a medical professional.
  • Participants who can have children must meet the following conditions:
    • Have a negative urine pregnancy test on the first day of the study, if they can become pregnant.
    • Have used effective birth control or abstained from activities that could lead to pregnancy for at least 28 days before the study treatment, if they can become pregnant.
    • Agree to continue using effective birth control or abstain from such activities for 3 months after receiving the booster dose.
    • For participants with a female reproductive system:
      • Use hormonal birth control (such as pills, injections, or patches).
      • Use an intrauterine device (IUD).
      • Have a partner who has had a vasectomy (the partner should be the only partner).
      • Use condoms.
      • For participants with a male reproductive system:
        • Have had a vasectomy.
        • Agree to use condoms with partners who can become pregnant.

Who cannot join the trial?

10 criteria

  • Participants must not have any other serious health conditions that could interfere with the study.
  • Participants should not have a history of severe allergic reactions to any vaccine.
  • Participants must not be pregnant or planning to become pregnant during the study.
  • Participants should not be breastfeeding.
  • Participants must not have received any other investigational drug or vaccine within 30 days before the study.
  • Participants should not have a history of immune system disorders, which are conditions where the body's defense system against infections is not working properly.
  • Participants must not have a history of bleeding disorders, which are conditions that affect the way blood clots.
  • Participants should not have any current or recent infections that require treatment with antibiotics or antiviral medications.
  • Participants must not have a history of drug or alcohol abuse within the past year.
  • Participants should not have any condition that, in the opinion of the study doctor, makes them unsuitable for the study.
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Investigated drugs

  • PHH-1V81

    is a new vaccine being tested as a booster shot for people who have already been vaccinated against COVID-19. This vaccine is designed to help the body recognize and fight the virus more effectively, especially against a specific variant called Omicron XBB.1.16. The goal is to see if this new booster can safely increase the body's immune response, helping to protect against COVID-19.

  • Comirnaty

    is a COVID-19 vaccine that has already been approved and used widely. In this trial, it serves as a comparison to the new vaccine, PHH-1V81. By comparing the two, researchers aim to determine if the new vaccine is as safe and effective as Comirnaty in boosting the immune system's ability to fight the virus.

What is already known about the treatment

PHH-1V81 – This medication is administered as a booster vaccine through an injection, specifically designed to enhance immunity against COVID-19. It is currently being studied in clinical trials to evaluate its safety and effectiveness in adults who have already received a primary COVID-19 vaccination and at least one booster dose of an mRNA vaccine. The main purpose of this vaccine is to boost the body's immune response to the virus, particularly against the Omicron XBB.1.16 variant. It works by using a recombinant protein that helps the immune system recognize and fight the virus more effectively. This vaccine falls under the category of immunological agents, which are used to stimulate or restore the ability of the immune system to fight infections.

Investigated diseases

COVID-19 disease – COVID-19 is an infectious disease caused by the SARS-CoV-2 virus. It primarily affects the respiratory system, leading to symptoms such as fever, cough, and difficulty breathing. The disease can progress to more severe respiratory issues, including pneumonia and acute respiratory distress syndrome. COVID-19 can also affect other systems in the body, potentially causing symptoms like fatigue, muscle pain, and loss of taste or smell. The progression of the disease varies widely among individuals, with some experiencing mild symptoms and others developing severe complications. The virus spreads mainly through respiratory droplets from coughs, sneezes, or talking.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2023-508458-25-00Protocol codeHIPRA-HH-14Estimated enrolment612 patientsSponsorHipra Scientific S.L.

sourced from the EU Clinical Trials Register and site verification

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