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Efficacy and safety of the investigational mRNA influenza vaccine gskvx000000077430 (drug combination) in adults ≥ 65 years

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

Influenza is a contagious respiratory illness that can cause fever, cough, body aches, and serious complications, especially in adults aged 65 years and older. The study evaluates a new vaccine that uses mRNA technology, identified by the code GSKVX000000077430, and compares it with a standard trivalent influenza vaccine that protects against three flu strains, including the subtypes H1N1, H3N2 and the lineage B/Victoria.

The purpose of the trial is to determine whether the new vaccine works at least as well as the standard vaccine in preventing flu illness and to assess its safety. Participants are randomly assigned to receive either the new vaccine or the standard one, and the study is conducted without the participants or the staff knowing which injection was given.

Each participant receives a single intramuscular injection and is then observed for a week to record any local or systemic reactions such as pain at the injection site, fever, or fatigue. After the initial week, participants are monitored throughout the flu season, which lasts about six months, to see whether they develop laboratory‑confirmed flu infections. Any serious health events are recorded up to the end of the season.

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

    Enrollment and consent

    You will be asked to read information about the study and sign a consent form that confirms you agree to take part.

    The study includes adults who are 65 years of age or older and who have not had a recent influenza vaccination.

  2. Step 2

    Baseline assessment and randomization

    A study staff member will collect basic health information, check your medical history, and perform a brief physical check.

    After the assessment you will be randomly assigned to receive either the investigational mRNA vaccine or the standard influenza vaccine; you will not know which one you receive.

  3. Step 3

    Vaccine injection

    You will receive a single dose of 0.5 milliliter of vaccine by intramuscular injection (injection into a muscle).

    The investigational product is described as a dispersion for injection, while the comparator is a suspension for injection; both are given in a pre‑filled syringe.

    The injection is administered in one arm and takes only a few seconds.

  4. Step 4

    Immediate observation

    After the injection you will remain in the clinic for a short period (typically about 15 minutes) so staff can watch for any immediate reactions such as redness, swelling, or feeling faint.

  5. Step 5

    Daily symptom diary (days 1‑7)

    For the first seven days, including the day of injection, you will record any local reactions at the injection site (such as pain, redness, or swelling) and any systemic symptoms (such as fever, headache, or muscle aches).

    These are called solicited events because the study specifically asks you to look for them.

    You can use a paper diary or an electronic tool provided by the study.

  6. Step 6

    Report any side effects (days 1‑28)

    During the first 28 days after vaccination you should report any health problems that were not asked about in the daily diary; these are called unsolicited adverse events.

    If you notice anything unusual, you can contact the study team by the method they gave you.

  7. Step 7

    Monitor for flu illness (starting day 14)

    Starting 14 days after the injection, you will be monitored for signs of influenza‑like illness that is confirmed by laboratory testing.

    If you develop symptoms such as fever, cough, or sore throat, you should inform the study staff so a test can be performed.

  8. Step 8

    Long‑term safety follow‑up (up to 180 days)

    The study will continue to follow you for at least 180 days, covering the entire influenza season.

    During this period you may be asked to attend additional visits or complete questionnaires to capture any serious adverse events or events of special interest.

    These visits help determine the overall safety of the vaccine over time.

Who can join the trial?

4 criteria

  • Be able to follow the study rules, such as filling out an electronic diary (eDiary), attending follow‑up visits, using a phone or other electronic device for study contact, and collecting your own nasal swab samples, either by yourself or with help from a caregiver.
  • Give written or digital informed consent, or have a legally authorized representative (LAR) sign on your behalf, before any study procedures are done.
  • Be a healthy person or have a chronic medical condition that is considered medically stable, meaning the illness has not needed major changes in treatment or a hospital stay for worsening symptoms in the past three months. Chronic conditions can include long‑lasting diseases of the metabolism, heart, lungs, kidneys, liver, nerves, or blood.
  • Be a male participant or a female participant who cannot become pregnant (non‑childbearing potential) and be at least 65 years old at the time the study vaccine is given.

Who cannot join the trial?

6 criteria

  • You cannot take part if you have had a influenza infection that was confirmed by a test within the last 180 days (about 6 months).
  • You cannot take part if you have a condition that weakens your immune system (immunosuppressive or immunodeficient condition). People with HIV are allowed only if their HIV is well‑controlled: they must have been on the same antiretroviral medicines for at least 6 months, have a CD4 cell count of 200 or higher, and have an undetectable viral load (less than 50 copies of HIV‑RNA per milliliter).
  • You cannot take part if you have ever had inflammation of the heart muscle (myocarditis) or the lining around the heart (pericarditis) that was judged to be caused by an mRNA vaccine.
  • You cannot take part if you have an active or unstable serious lung (pulmonary), heart (cardiovascular), liver (hepatic), hormone (metabolic/endocrine), kidney (renal), or mental health (psychiatric) condition, based on your medical history and exam.
  • You cannot take part if you received a flu (influenza) vaccine within the past 180 days or if you plan to receive a flu vaccine at any time during the study.
  • You cannot take part if you have been taking medicines that change the immune system (immune‑modifying drugs) for more than 14 consecutive days, or if you plan to use long‑acting immune‑modifying treatments during the study. This includes taking high‑dose oral steroids (equivalent to prednisone 20 mg or more per day) for more than 14 days in the 90 days before the study. Inhaled, joint‑injection, or skin‑applied steroids are allowed. Long‑acting drugs such as immunotherapy (for example, TNF‑inhibitors), monoclonal antibodies, or cancer‑fighting medicines also exclude participation.
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Investigated drugs

  • Trivalent influenza vaccine (Efluelda TIV‑HD)

    is a seasonal flu shot that contains three inactivated flu viruses – one type B strain and two type A strains (H1N1 and H3N2). It is given as a single injection into the muscle. In this study it serves as the active comparator, meaning it is the standard flu vaccine used to see how well the new vaccine works in preventing flu‑like illness in older adults.

  • Investigational mRNA‑based seasonal influenza vaccine (GSKVX000000077430, GSKVX000000077508, GSKVX000000077506, GSKVX000000077510, GSKVX000000077509, GSKVX000000077507)

    is a new vaccine that uses messenger RNA technology to teach the body’s immune system to recognize the same flu viruses that are in the standard vaccine. It is also given as a single intramuscular injection. In the trial this product is the test vaccine, and the study is looking at whether it is at least as effective as the standard trivalent flu shot at preventing laboratory‑confirmed flu‑like illness in people aged 65 and older, while also monitoring its safety and any side effects.

What is already known about the treatment

  • Efluelda TIV‑HD, suspension for injection in pre‑filled syringe

    This vaccine is given as a 0.5 ml intramuscular injection using a pre‑filled syringe containing a suspension of inactivated influenza viruses. It is an approved, commercially available trivalent influenza vaccine that is widely used each flu season. The vaccine works by presenting the body with harmless pieces of the flu virus, prompting the immune system to make protective antibodies against the three strains included. It is classified as an inactivated influenza vaccine (purified antigen).

  • GSKVX000000077430, GSKVX000000077508, GSKVX000000077506, GSKVX000000077510, GSKVX000000077509, GSKVX000000077507

    This investigational product is administered as a 0.5 ml intramuscular injection of a dispersion designed to deliver messenger RNA encoding influenza hemagglutinin proteins. It is currently in a phase 3 clinical trial and has not yet received regulatory approval. The vaccine aims to protect older adults from seasonal influenza by causing the body’s cells to produce the viral protein, which then triggers an immune response and antibody formation. It belongs to the pharmacological class of mRNA‑based influenza vaccines.

Investigated diseases

Influenza - Influenza is an acute viral infection of the respiratory tract caused by influenza viruses. It typically begins with a sudden fever, chills, muscle aches, and a sore throat, followed by a cough and fatigue. Symptoms usually appear within one to four days after exposure and peak within a few days. The illness generally lasts about a week, after which most people feel better as the immune system clears the virus. In some cases, the infection can spread from the upper to the lower airways, leading to a more prolonged cough and feeling of weakness.
Trial detailsLast updated 7 Oct 2026
Age65+ yearsPhasePhase IIITrial ID2026-526682-14-00Protocol code218130Estimated enrolment54 000 patientsSponsorGlaxoSmithKline Biologicals

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