AuthorisedPhase I and Phase II (Integrated)- First administration to humansInterventional

Phase 1/2, first-in-human, randomized, double-blind, reference-controlled study to evaluate the safety and immunogenicity of an extemporaneously mixed Combo Inactivated Influenza Vaccine (Green Cross [GC]-IIV; 15µg of each hemagglutinin [HA])/OVX836 (480µg), in comparison to GC-IIV (15µg of each HA) concomitantly administered with OVX836 (480µg), GC-IIV alone (15 µg each HA), OVX836 alone (480µg), and a licensed reference trivalent IIV (Vaxigrip®; 15µg of each HA), administered intramuscularly (IM) in healthy participants

Flu is a common respiratory illness that can cause fever, body aches, and serious complications in vulnerable people. Current flu jabs are updated every year, but scientists are looking for ways to provide broader and longer-lasting protection. This trial is testing an experimental combination vaccine. It blends a standard seasonal flu jab with a new vaccine component called OVX836, which is designed to help the immune system recognise parts of the flu virus that do not change as frequently. Healthy volunteers aged 18 and older will receive a single injection in their arm muscle. Researchers will compare this new combination against standard flu vaccines and each component on its own. The main goals are to check for any side effects and to see how many protective antibodies the body produces over a six-month follow-up period.

At a glance

Status

Authorised

Phase

Phase I and Phase II (Integrated)- First administration to humans

Sponsor

Osivax

Enrolment target

250

Start

04 Sep 2026

Influenza disease

What is this study about?

Influenza, commonly known as the flu, affects millions of people each winter. While standard annual flu jabs offer good protection, the virus mutates regularly, meaning vaccines must be redesigned every year. Researchers are actively working on next-generation flu jabs that could offer broader and stronger protection against multiple strains.

This early-phase trial is evaluating an experimental combination vaccine. It brings together two elements: an inactivated seasonal flu vaccine (GC-IIV) and a novel vaccine candidate known as OVX836. OVX836 is designed to target internal parts of the virus that remain stable across different flu seasons. By combining these two approaches, researchers hope to stimulate both antibodies and specialised white blood cells called T-cells.

Because this is an early-stage study, the primary focus is safety. Researchers want to make sure the combined injection is well tolerated compared with standard, licensed flu jabs such as Vaxigrip. Volunteers are randomly placed into different groups to test the mixture, the separate components, or standard care, allowing scientists to gather precise and unbiased safety data.

Key takeaways

Tests a new combination flu vaccine aimed at providing broader immune protection.
Open to healthy adults aged 18 and older.
Involves a single arm injection and follow-up check-ups over about six months.
Compares the new vaccine against an established, approved seasonal flu jab.
Monitors participants closely for safety, side effects, and blood antibody levels.

Who may be eligible?

This trial is open to healthy men and women aged 18 and over. Because the study is focused on establishing safety in humans, volunteers generally need to be in good physical health without unstable, serious, or chronic medical conditions.

You may not be able to take part if you have a known severe allergy to vaccines or their ingredients, or if you have a condition affecting your immune system. You may also be excluded if you are currently taking medications that alter immune function or if you have recently had another flu vaccine.

A doctor from the research team will carry out health assessments and basic tests before you join to confirm whether taking part is safe and appropriate for you.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I am at least 18 years of age.
I consider myself to be in good general health.
I have no known severe allergies to vaccines or flu jab ingredients.
I do not have an active illness or a weakened immune system.
I am willing and able to attend clinic visits and have blood tests over a six-month period.

Answer every question to see your result.

What does participation involve?

Taking part in this study lasts for around six months (180 days). At your first appointment, the clinic team will check your medical history, perform a physical examination, and take baseline blood tests. If you are eligible, you will receive a single injection into your upper arm muscle.

For the first seven days after the injection, you will be asked to track any daily symptoms, such as soreness around the injection site, tiredness, or a mild temperature, using a diary. You will then return for scheduled check-up visits, typically around Day 8, Day 29, and Day 180. During these visits, doctors will review your general health and take further blood samples to measure your immune response.

Potential risks and benefits

Taking part may provide protection against the flu strains covered by the trial vaccines, though this cannot be guaranteed. The study also helps scientists develop better vaccines for the future. Like all jabs, you may experience temporary side effects such as redness, swelling, or pain where the needle went in, as well as mild headaches or fatigue. Because one of the vaccines is experimental, unexpected reactions are possible, but you will be monitored closely by medical staff. Joining the study is entirely voluntary, and you are free to leave at any time without giving a reason and without your normal NHS care being affected.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Belgium

Common questions

What is the main goal of this clinical trial?

The study aims to check if a new combination flu vaccine is safe, well tolerated, and able to trigger a good immune response compared to existing flu jabs.

Will I definitely receive the new combination vaccine?

Not necessarily. Participants are placed into different groups by chance (randomised). You might receive the combination jab, one of the components on its own, or a standard licensed flu vaccine.

How is the vaccine given?

It is given as a single injection into the muscle of your upper arm, exactly like a routine annual flu jab.

Do I have to pay to take part in this study?

No. The trial vaccines and all study-related health checks are provided free of charge, and participants are often reimbursed for reasonable travel expenses.

Can I leave the study early if I change my mind?

Yes. Taking part is completely voluntary. You can withdraw your consent at any point without it affecting your regular healthcare.