CompletedPhase IInterventional

A clinical trial to assess three self-amplifying ribonucleic acid (saRNA) vaccines against Ebola, Marburg, and Lassa fever viruses

This study, called EML-Vac, is testing three new self-amplifying RNA vaccines designed to protect against serious viruses: Ebola, Marburg, and Lassa fever. These viruses can cause severe illnesses in people, mainly in parts of Africa. The main goal is to check how safe these new vaccines are when given alone or together. It's also looking at how well a person's immune system responds to the vaccines. This is an early-stage study, meaning it's the first time these particular vaccines are being tested in humans. They will not be checking if the vaccines actually prevent infection yet. Healthy adults aged 18 to 50 can take part, but certain medical conditions or pregnancy would mean you cannot join.

At a glance

Status

Completed

Phase

Phase I

Sponsor

Imperial College London

Enrolment target

Start

27 Jan 2026

Estimated completion

31 Mar 2026

Healthy volunteers

What is this study about?

This research study, called EML-Vac, is looking into new types of vaccines to protect against three very serious viruses: Ebola, Marburg, and Lassa fever. These viruses are found mostly in some parts of Africa and can cause severe illness, sometimes called viral haemorrhagic fever. Finding effective ways to prevent these diseases is really important.

The vaccines being tested are called 'self-amplifying RNA' vaccines. This is a new approach to vaccination, and these particular vaccines have never been given to people before. The main purpose of this study is to find out if these vaccines are safe for humans, both when given on their own and when combined. Researchers will also observe how the body's immune system reacts to these vaccines. They want to see if the vaccines can kick-start an immune response that might protect against these viruses in the future.

It's important to understand that this study is an early step in vaccine development. While they will be checking the immune response, this study will not involve exposing people to the actual viruses. So, it won't tell us if the vaccines definitely prevent infection yet. It's all about making sure they are safe and understanding how they work in the body before moving on to larger studies.

Key takeaways

This is a first-time-in-human study for new Ebola, Marburg, and Lassa fever vaccines.
The main goals are to check vaccine safety and how the immune system responds.
Healthy UK adults aged 18-50 can take part, with some exclusions.
Participation involves two injections, symptom tracking, and blood tests over about a year.
No direct health benefits, but your participation aids future vaccine development.
Potential side effects are generally mild, like soreness or fatigue.

Who may be eligible?

This study is looking for healthy adults aged between 18 and 50 years old to take part. Generally, you should be in good health to be considered.

There are also some important things that would mean you can't join. For example, if you have certain existing medical conditions, a history of severe allergies, or if you are pregnant, you won't be able to participate. Women who could become pregnant must agree to use reliable birth control methods throughout the study and have regular pregnancy tests. Men must also use condoms during the study period.

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 between 18 and 50 years old?
Are you generally in good health?
Are you able to attend appointments at Chelsea and Westminster Hospital?
If you could become pregnant, are you willing and able to use reliable birth control and have pregnancy tests?
Are you willing to avoid other vaccines for 4 weeks before and after study injections?
Are you willing to avoid donating blood for at least three months after the study?
Are you willing to complete online symptom diaries?

Answer every question to see your result.

What does participation involve?

If you decide to take part, you'll be randomly put into one of five different groups. Each group will receive different combinations of the Ebola, Marburg, and Lassa RNA vaccines, or a 'placebo' which is an inactive mock treatment. You'll receive two injections into a muscle, one at the very beginning of the study and another 12 weeks later.

During the study, you'll be asked to keep track of any symptoms you experience using an online diary. You'll also need to provide blood samples several times over a year so that the researchers can check how your immune system is responding. The study team will closely monitor you for any side effects and will follow up if you happen to miss a scheduled visit. The study is expected to run from July 2025 to March 2027.

Potential risks and benefits

There aren't any direct health benefits for people joining this study. However, by taking part, you would be helping science and potentially contributing to new vaccines that could protect many others from these dangerous viruses in the future. As for risks, you might experience mild to moderate side effects, such as soreness where the injection was given, feeling tired, a headache, or muscle pain. More rarely, there could be allergic reactions, a fever, or inflammation. Giving blood samples might cause some bruising or discomfort too. It's also important to know that you wouldn't be able to donate blood for at least three months after the study ends. You are free to withdraw from the study at any time without giving a reason.

Locations (1)

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

Chelsea and Westminster Hospital Clinical Research Facility (CRF) at St. Stephen’s Centre
City only
London, England

Common questions

What are 'self-amplifying RNA' vaccines?

These are a newer type of vaccine that work by giving your body instructions to make a small part of the virus. This then teaches your immune system how to fight off the real virus if you ever encounter it. 'Self-amplifying' means the instructions multiply a bit, so you might need a smaller dose.

Will I get Ebola, Marburg, or Lassa fever from the vaccine?

No, these vaccines only contain small parts of the virus's genetic code, not the actual live virus. They cannot give you the disease being vaccinated against.

What is a 'placebo'?

A placebo is an inactive substance, like a sterile saline solution, that looks exactly like the actual vaccine but contains no active ingredients. It's used to compare the effects of the active vaccine.

How long will I be involved in the study?

You'll be involved for about a year from your first injection, with follow-up visits and blood tests during that time.

Who is running this study?

The study is being run from the Chelsea and Westminster Hospital Clinical Research Facility at St. Stephen’s Centre, and it's funded by Innovate UK.

How to find out more

Marta Boffito

marta.boffito@nhs.net +44 208 3156148 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.