WHO Launches First Trial of Ebola Antiviral in DRC

The WHO-backed EBO-PEP trial is testing Gilead Sciences' oral antiviral obeldesivir as post-exposure prophylaxis against the Bundibugyo Ebola strain. The trial reflects the WHO-PAHO emergency-response architecture underpinning Mexico's newly signed Country Cooperation Strategy 2026–2030, which prioritizes regional biologics self-sufficiency and regulatory harmonization.  

The World Health Organization (WHO) confirmed on July 14, 2026, that the first clinical trial testing an antiviral drug as post-exposure prophylaxis against the Bundibugyo strain of Ebola has begun in the Democratic Republic of the Congo (DRC) and Uganda. The trial, called EBO-PEP, evaluates obeldesivir, an oral antiviral developed by California-based Gilead Sciences, among people who had direct contact with confirmed cases within the preceding five days but show no symptoms.

"If effective among high-risk contacts after exposure, this could mark a major step forward," says Tedros Adhanom, Director General, WHO, in a statement confirming the trial's launch. No approved vaccine or treatment currently exists for the Bundibugyo variant, which the WHO designated a public health emergency of international concern on May 17, 2026.

The outbreak has infected more than 1,759 people and killed over 600, according to figures from the DRC's National Institute of Public Health cited by Africa CDC and ALIMA, the nongovernmental organization operating treatment centers in Ituri Province, where more than 90% of cases are concentrated. Cases have also spread to four other DRC provinces and neighboring Uganda. The National Institute for Biomedical Research in Kinshasa, the ANRS Emerging Infectious Diseases unit of Inserm, and ALIMA are jointly running the trial, which has been in preparation since 2024 as part of a broader platform designed to test post-exposure strategies against filoviruses across Sub-Saharan Africa, including Guinea, Liberia, and Sierra Leone.

EBO-PEP aims to enroll close to 1,000 participants aged 12 and older at prophylaxis centers adjacent to Ebola treatment facilities in Bunia and Rwampara. Investigators expect the trial to run for several months and potentially into 2027 before yielding conclusive results. It operates alongside a separate WHO-backed trial, PARTNERS, which is testing the monoclonal antibody MBP134 and the antiviral remdesivir in patients already infected, according to Science/AAAS. Together, the two trials represent a coordinated scientific response covering prevention, post-exposure protection, and treatment.

For Mexico's health and life sciences sector, the trial illustrates the type of coordinated, WHO-anchored emergency-response infrastructure that regional health authorities increasingly reference in domestic planning. Mexico's Ministry of Health signed the Country Cooperation Strategy 2026–2030 with the Pan American Health Organization (PAHO) and WHO earlier this month, a framework that explicitly prioritizes regional self-sufficiency in biologics, medical supplies, and regulatory harmonization, according to Mexico Business News. That agreement builds on a PAHO/WHO technical mission earlier this summer that assessed Mexico's Universal Health Service and identified areas for institutional cooperation on governance and health systems strengthening, as Mexico Business News also reported.

Gilead Sciences, the developer of obeldesivir, maintains an established regulatory and commercial presence in Mexico. A successful EBO-PEP outcome could accelerate global stockpiling and regulatory pathways for post-exposure antivirals, a development regulators in Mexico and across Latin America are likely to monitor as they align approval timelines with international health emergency protocols. The trial's progress will also be closely tracked by international health bodies working to formalize pandemic and epidemic preparedness frameworks in the Americas, an agenda in which Mexico has taken an increasingly active role over the past year.