Scientists probe how long monkeypox vaccine immunity lasts
NCT ID NCT06366672
First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 1 time
Summary
This study looks at how long the JYNNEOS vaccine protects people from smallpox and monkeypox. Researchers will measure immune responses in the blood, lungs, skin, and bone marrow of 20 healthy adults who receive the vaccine. The goal is to understand the durability of protection, which could guide future booster shot recommendations.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- JYNNEOS (smallpox and monkeypox vaccine)
- What this could lead to
- If successful, this could help determine how often booster shots are needed for long-lasting protection against smallpox and monkeypox.
- What could go wrong
- This is a very small early-phase study with only 20 healthy participants, so results may not apply to the general population or those with weakened immune systems.
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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Early phase 1
The earliest testing in people: a first look at safety, in a very small group.
- Participants
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About 20 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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Jun 2024
- Expected to finish
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Dec 2026
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
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: * 18-60 year old otherwise healthy participants Exclusion Criteria: * Prisoners * Participants unable to provide full written informed consent * Previous receipt of a smallpox or monkeypox vaccine * Previous infection with monkeypox * Receipt of any vaccine in the 28 days prior to the first study procedure or planned receipt of any vaccine outside of those provided in the current study before completion of the study day 42 visit. * Immunocompromise (primary or secondary due to other medical conditions or medications) * Previous organ transplant * Active malignancy * Pregnancy * \< 4 weeks post-partum or actively breastfeeding * Female participants who are not actively on hormonal contraception or do not have an intrauterine device in place * Body Mass Index \> 40 * Current smokers * History of a known chronic pulmonary, cardiovascular, renal, hepatic, hematologic or metabolic disorder. Participants with isolated treated hypertension as the only cardiovascular disorder may be included in the study. * History of a chronic neurologic or neurodevelopmental condition. This does not exclude potential participants with chronic back pain or previous disk herniation/back surgery, only participants with documented weakness, quadriplegia or paraplegia. This exclusion criterion also does not exclude from the study participants with recurrent migraine headaches as the only chronic neurologic condition. * Pulse oxygen saturation value of 92% or less on room air at study enrollment or on the day of bronchoscopy * Any significant infiltrate or pleural effusion on upright posterior-anterior and lateral chest x-ray imaging performed on the day of bronchoscopy * International Normalized Ratio value greater than 1.4 or a Partial Thromboplastin Time value of greater than 40 seconds at study enrollment * Platelet count of less than 100,000 at study enrollment
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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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Washington University in Saint Louis School of Medicine Emergency Care and Research Core
St Louis, Missouri, 63110, United States
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