Ongoing, recruitingTherapeutic exploratory (Phase II)Interventional

A Phase 2a randomized, observer-blind, study to evaluate the immunogenicity and safety of mRNA-based multivalent seasonal influenza vaccine candidates in adults 18 years of age and older.

This research is looking into new types of flu vaccines for adults aged 18 and older. The main goal is to find out how well these new vaccines help your immune system build protection against the flu virus. We're also carefully checking for any side effects to make sure the vaccines are safe. The study compares these new vaccines to a standard flu vaccine that's already used. By doing this, we hope to learn more about how well these new flu vaccines work and if they could be useful for preventing flu in the future. Participants will receive one of the vaccines and their health will be observed closely over several months.

At a glance

Status

Ongoing, recruiting

Phase

Therapeutic exploratory (Phase II)

Sponsor

GlaxoSmithKline Biologicals

Enrolment target

150

Start

09 Sep 2025

Influenza Human

What is this study about?

This study is a research project designed to test new flu vaccines. These vaccines are made using a special method called "mRNA technology," which is a new way to help your body learn to fight off viruses. The researchers want to see how well different versions of these new mRNA flu vaccines work.

The main things they are looking at are: how well your body makes antibodies (special proteins that fight off infections) after getting the vaccine, and whether the vaccines cause any unwanted side effects. They will compare these new vaccines to a flu vaccine that's already approved and commonly used. This helps them understand if the new vaccines are as good or better at protecting against the flu and if they are safe.

The study is called a "Phase 2a" study. This means it's an early stage of testing where researchers are trying to get a better understanding of the vaccine's effects in a smaller group of people, before potentially moving on to larger studies. The overall goal is to find safe and effective ways to protect people from the flu each year.

Key takeaways

This study is testing new flu vaccines in adults.
It aims to see how well the vaccines work and if they are safe.
Participants will receive a vaccine and have their health checked regularly.
The study lasts about six months.
It could help improve future flu protection.

Who may be eligible?

To be able to join this study, you need to be an adult, aged 18 years or older. Both men and women are welcome to participate.

There might be other health requirements or conditions that mean someone cannot join, even if they are over 18. These will be discussed in detail by the study team.

It's important that you discuss your full medical history with the study doctor to make sure this study is right 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.

Are you 18 years old or older?
Are you a man or a woman?
Do you have a general good state of health?
Are you willing and able to attend all study visits?

Answer every question to see your result.

What does participation involve?

If you decide to take part in this study, you would receive an injection of one of the study vaccines. This injection will be given by a healthcare professional. You will then have several visits to the clinic over a number of months. During these visits, the study team will take blood samples to measure how your body is responding to the vaccine and check for any antibodies against the flu. They will also carefully monitor your health for any side effects. You'll be asked about how you're feeling and if you've experienced any changes. The study will involve a total follow-up period of about six months.

Potential risks and benefits

Potential benefits of taking part could include contributing to scientific knowledge about new flu vaccines and potentially receiving protection against some types of flu from the study vaccine. However, there's no guarantee the vaccine will protect you. Potential risks include common side effects like soreness, redness, or swelling where you got the injection, or general symptoms like headache or feeling tired, similar to other vaccines. More serious side effects are possible but usually rare. You have the right to withdraw from the study at any time, for any reason, without it affecting your medical care.

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 an mRNA vaccine?

An mRNA vaccine teaches your body's cells how to make a harmless piece of a virus, which then helps your immune system learn to fight off the actual virus if you encounter it.

Why is this study important for flu?

This study is important because it's looking into new ways to make flu vaccines more effective, which could lead to better protection against the flu each year.

Will I know if I got the new vaccine or the standard one?

Because this study is "observer-blind," neither you nor the study staff will know which vaccine you receive until after the study is complete, to keep the results unbiased.

How long will I be in the study?

Your participation in the study, including follow-up, will last for about six months after you receive the vaccination.

Will I have to pay to join the study?

No, you will not have to pay to participate in the study. All study-related care and vaccines are provided free of charge.