AuthorisedTherapeutic confirmatory (Phase III)Interventional

A Phase 3, Parallel, Randomized, Modified Double-Blind, Active-Controlled, Multi-Arm Study to Assess the Safety and Immunogenicity of a Combination Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Recombinant Spike and High-Dose Inactivated Influenza Vaccine with Matrix-M Adjuvant in Adult Participants 60 Years of Age and Older

Every winter, respiratory illnesses like flu and COVID-19 can cause serious illness, particularly in older adults. Currently, staying protected often means having two separate appointments and two different jabs. This Phase 3 clinical trial is testing a new combination vaccine that brings both protections together into one single injection. Researchers are comparing this combined jab against standard flu and COVID-19 vaccines given on their own, as well as a harmless salt-water dummy injection to ensure fair comparison. The study will measure the levels of protective antibodies in the blood after vaccination. It will also closely monitor safety by checking for common reactions like arm soreness or mild fever. The overall goal is to see if a single combined jab is just as safe and effective as having two separate injections, potentially making winter protection simpler and quicker.

At a glance

Status

Authorised

Phase

Therapeutic confirmatory (Phase III)

Sponsor

Sanofi Vaccines US Inc.

Enrolment target

5,945

Start

05 Oct 2026

COVID-19, Influenza

What is this study about?

Flu and COVID-19 are both common viral infections that spread easily, especially during the colder autumn and winter months. For many people, particularly older adults, these viruses can lead to chest infections, hospital stays, or other serious health problems. Vaccines provide the best defence by training your immune system to recognise and fight off the viruses before they can make you unwell.

At present, people who are eligible usually receive one jab for flu and another for COVID-19. This study is testing a new vaccine that combines both into a single injection. It uses parts of the virus proteins alongside an ingredient called an adjuvant, which helps boost your body's natural immune response. Researchers want to find out whether this single jab works just as well at building protective antibodies as the existing vaccines given separately.

This is a Phase 3 study, which is the final testing stage before a new vaccine can be approved for general use. By taking part, volunteers help scientists discover whether combining these vaccines is safe and reliable. If successful, having one combined jab could make winter vaccination programmes much easier for both patients and healthcare staff across the UK.

Key takeaways

Testing a single combined jab that protects against both flu and COVID-19.
A Phase 3 study comparing the new jab against existing, separate vaccines.
Aims to check safety, common side effects, and immune antibody levels.
Particularly focused on older adults who benefit most from seasonal protection.
Participation is entirely voluntary and includes regular health check-ups.

Who may be eligible?

This study is designed for adults, with a particular focus on people aged 60 and older. Because older adults are at a higher risk of complications from both flu and COVID-19, testing vaccines in this age group helps ensure the jab offers strong, lasting protection where it is needed most.

You may not be eligible to take part if you have had a severe allergic reaction to vaccines in the past, or if you currently have an active, serious illness. The study team will also ask about your previous vaccinations and any long-term medical conditions to decide if the study is safe for you.

Before you join, a doctor from the study team will go through your medical history in detail. They will explain all entry requirements clearly and answer any questions to help you decide if the trial 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.

I am an adult aged 60 or older (or meet the study's adult age criteria).
I am interested in receiving protection against both flu and COVID-19.
I have not had a severe allergic reaction to vaccines in the past.
I am willing to attend clinic appointments and have occasional blood tests.
I can keep a simple diary of any symptoms for about a week after the injection.

Answer every question to see your result.

What does participation involve?

Taking part in this study involves several clinic visits over a set period, typically lasting several months. At your first visit, the study team will check your health and take a small blood sample. You will then receive your study injection into the muscle of your upper arm. Because this is a randomised study, a computer will choose which jab you receive, and you may receive the new combination vaccine or standard separate vaccines.

After your injection, you will be asked to stay in the clinic for a short observation period to make sure you feel well. You will then be given a symptom diary to record any side effects—such as arm soreness, redness, headache, or tiredness—for the first eight days. You will attend follow-up clinic visits where the team will check your health and take further blood samples to measure how many protective antibodies your body has made.

Potential risks and benefits

Taking part may help protect you against flu and COVID-19, and your involvement helps develop simpler vaccines for the future. However, there are potential side effects. Common reactions include soreness or swelling where you had the jab, mild fever, muscle aches, or feeling tired for a few days. As with any vaccine, unexpected or allergic reactions can happen, though the medical team monitors you closely. Joining the study is completely voluntary, and you are free to leave at any point without it affecting your regular NHS care.

Locations (6)

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

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Unverified
Belgium
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Unverified
Poland
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Unverified
Spain
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Unverified
Portugal
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Unverified
France
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Unverified
Germany

Common questions

Why are researchers trying to combine flu and COVID-19 jabs?

Combining them into a single injection means you only need one appointment and one needle prick to get protected against both viruses for the winter season.

Can I catch flu or COVID-19 from these vaccines?

No. The vaccines used in this study do not contain live viruses, so they cannot give you flu or COVID-19.

Will I definitely get the new combination vaccine?

Not necessarily. Participants are placed into different groups by chance. Some receive the combination jab, while others receive standard approved vaccines or a harmless salt-water injection for comparison.

What happens if I feel unwell during the trial?

You will be given contact details for the study medical team. They are available to support you, assess your symptoms, and provide care if needed.

Can I leave the study if I change my mind?

Yes. You have the right to withdraw from the study at any time, for any reason, and your normal healthcare will not be affected.