Clinical trial tests antiviral drug to prevent Ebola infection following exposure during Congo outbreak

A trial launched in July is testing Gilead's experimental antiviral pill obeldesivir as a post-exposure preventive treatment for the Bundibugyo virus variant causing an outbreak in eastern Congo. Over 250 participants, including exposed health workers and family members of patients, have been enrolled in the study testing whether the medication can prevent disease development after suspected contact. The outbreak has killed approximately 4,000 people among 8,300 confirmed cases since May 2026.

The Bundibugyo virus outbreak in eastern Congo represents a particularly challenging public health crisis due to the absence of established vaccines or approved treatments. Since May 2026, the disease has rapidly spread across seven provinces, with transmission patterns difficult to control through conventional contact-tracing methods. The experimental approach being tested—administering medication shortly after exposure rather than waiting for symptoms to emerge—represents a shift in strategy for managing this fast-moving outbreak that continues to overwhelm tracking and containment efforts.

Trial participants represent high-risk populations directly affected by the outbreak, including medical personnel treating patients and family members of confirmed cases. The study design, which enrolls only individuals exposed within five days but showing no symptoms, targets the critical window before viral replication reaches detectable levels. Daily monitoring for 21 days followed by extended follow-up allows researchers to track whether the intervention prevents disease progression in this vulnerable population exposed to confirmed cases.