New yellow fever vaccine shows promise in early trial
NCT ID NCT04142086
First seen Jun 26, 2026 · Last updated Jun 26, 2026
Summary
This Phase 1 study tested a new yellow fever vaccine (vYF) in 73 healthy adults aged 18 to 60. The goal was to check the vaccine's safety and how well it triggers an immune response at three different doses. Participants were monitored for side effects and antibody levels over six months. The results will help decide if larger studies are warranted.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- yellow fever vaccine (vYF)
- What this could lead to
- If successful, this could lead to a new, safer yellow fever vaccine that is easier to produce.
- What could go wrong
- This is an early Phase 1 trial with only 73 healthy adults, so results may not apply to everyone. The vaccine may not trigger a strong enough immune response or could have unexpected side effects.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Phase 1
The first testing in people. Mainly checks safety and dose, usually in a small group.
- Participants
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73 people
The number who actually took part.
- Started
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Jan 2020
- Finished
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Jun 2021
- Lead sponsor
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A company
The lead sponsor is a pharmaceutical, biotech, or medical-device company.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 to 60 years
- Sex
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Anyone
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion criteria : * Aged 18 years up to 60 years on the day of inclusion * Able to read and understand the Informed Consent Form which has been signed and dated * Able to attend all scheduled visits and to comply with all trial procedures Exclusion criteria: * Participant is pregnant, or lactating, or of childbearing potential and not using an effective method of contraception or abstinence from at least 4 weeks prior to vaccination until at least 4 weeks after vaccination. To be considered of non-childbearing potential, a female must be pre-menarche , or post-menopausal for at least 1 year, or surgically sterile * Participation at the time of study enrollment (or in the 4 weeks preceding the trial vaccination) or planned participation during the present trial period in another clinical trial investigating a vaccine, drug, medical device, or medical procedure * Receipt of any vaccine in the 4 weeks preceding the trial vaccination or planned receipt of any vaccine in the 4 weeks following the trial vaccination * Previous vaccination against a flavivirus disease including YF with either the trial vaccine or another vaccine * Receipt of immune globulins, blood, or blood-derived products in the past 6 months * Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy, or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months) * Known history of flavivirus infection * Known systemic hypersensitivity to any of the vaccine components, eggs, or history of a life-threatening reaction to the vaccines used in the trial or to a vaccine containing any of the same substances * Known history or laboratory evidence of human immunodeficiency virus infection * Known history of hepatitis B or hepatitis C seropositivity * Personal of family history of thymic pathology (thymoma, thymectomy, or myasthenia) * Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily * Current alcohol abuse or drug addiction * Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion, including malignancy, such as leukemia or lymphoma * Moderate or severe acute illness/infection (according to investigator judgment) on the day of vaccination or febrile illness (temperature ≥ 100.4 F). A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided * Administration of any anti-viral within 2 months preceding the vaccination and up to the 6 weeks following the vaccination * Identified as an Investigator or employee of the Investigator or study center with direct involvement in the proposed study, or identified as an immediate family member (ie, parent, spouse, natural or adopted child) of the Investigator or employee with direct involvement in the proposed study * Planned travel in a YF endemic country within 6 months of investigational or control vaccine administration The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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Investigational Site Number 8400001
Silver Spring, Maryland, 20910, United States
More trials for these conditions
Other studies related to the condition(s) this trial covers.