Recruiting

Testing a new COVID-19 booster vaccine in healthy adults

Plain-English translation of NCT06255626 on ClinicalTrials.gov ↗ · Source last updated April 2025 · Translation generated June 2026 · How we translate trials

Phase 1/2 — A combined trial that checks safety and dosing while also starting to look at whether the treatment works.

What is this trial?

This study is testing a new COVID-19 booster vaccine called CD40.RBDv in healthy volunteers who have already been vaccinated against COVID-19. Researchers want to learn whether this medication is safe and whether it triggers a strong immune response. The vaccine comes in different versions — some with an immune-boosting additive and some without — and in different doses, so the trial will compare how well each version works.

Current COVID-19 vaccines work well, but scientists are exploring whether newer vaccines might offer better or longer-lasting protection. This medication is designed to be a new type of booster that could potentially improve how the immune system fights COVID-19.

Do you qualify?

You likely qualify if…

you are at least 18 years old and under 85
you have received a primary COVID-19 vaccine series plus at least one booster shot, with the last booster at least 6 months before joining
you are in good overall health with normal blood work and organ function
you are able to understand the study and sign consent forms
if you can become pregnant, you agree to use effective birth control during the study and test negative for pregnancy

You likely don't qualify if…

you have had a fever or COVID-19 symptoms in the past 4 weeks
you have taken immunosuppressive medications (drugs that weaken immunity) in the past 3 months
you have a history of severe reactions to vaccines or a bleeding disorder that would make injections unsafe
you have a serious medical condition such as cancer, heart disease, autoimmune disease, or uncontrolled asthma that might affect how your immune system responds
you are currently pregnant, breastfeeding, or plan to participate in another vaccine study at the same time

What participation looks like

You will receive one injection of the study vaccine at your first visit. Then, three months later, you may be randomly assigned to either receive a second dose of the same vaccine or no additional vaccine — this helps researchers see whether one dose or two doses works better. Throughout the study, you'll have blood tests to check your immune response and monitor for any side effects. The entire study lasts several months, with visits at specific timepoints to check your health and answer questions about how you've felt since your last injection.

AI-generated summary from trial data · Jun 15, 2026 · Not medical advice

Trial locations(2 sites)

France

Hopital Henri Mondor, Créteil

Hôpital Cochin, Paris