Could a Decades-Old smallpox vaccine stop mpox? colombia trial aims to find out

NCT ID NCT06223919

Ongoing Prevention Sponsor: Universidad Nacional de Colombia Source: ClinicalTrials.gov ↗

First seen Jun 26, 2026 · Last updated Jun 26, 2026 · Updated 1 time

Summary

This Phase 3 trial in Colombia tests the LC16m8 vaccine, originally developed for smallpox, to see if it can prevent mpox in people at high risk, such as men who have sex with men and those with HIV. About 8,686 participants will be randomly assigned to get the vaccine right away or after a delay. Researchers will compare infection rates and side effects between the groups over 180 days.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: LC16m8 (live attenuated vaccinia virus vaccine)
What this could lead to: If successful, this vaccine could help prevent mpox in high-risk populations, including people with HIV, and reduce severe illness.
What could go wrong: Mpox cases have dropped recently in Colombia, making it harder to measure effectiveness. The trial is also open-label, which can introduce bias.

This is an AI summary of the original study and may miss details. Read our disclaimer.

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Conditions

The condition(s) this trial relates to.

monkeypox prevention target

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

MONKEYPOX

Contacts and locations

Locations

Clinica Universitaria Colombia - Centro Medico Teusaquillo

Bogotá, Bogota D.C., Colombia
Hospital Universitario San Ignacio

Bogotá, Bogota D.C., Colombia
Infecto Clinicos

Bogotá, Bogota D.C., Colombia

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