Trial of potential Ebola antiviral under way: WHO

Trial of potential Ebola antiviral under way: WHO

The World Health Organization (WHO) has launched a clinical trial to test an antiviral drug's effectiveness in people exposed to the Bundibugyo virus (BVD), a deadly Ebola strain currently spreading through the Democratic Republic of Congo (DRC) and neighboring Uganda. The trial, titled EBO-PEP, focuses on post-exposure prophylaxis for individuals who have had contact with confirmed BVD cases.

The experimental drug, obeldesivir, was developed by the US pharma firm Gilead Sciences. Administered orally, the antiviral has previously demonstrated efficacy in pre-clinical models against viruses within the wider filovirus family that cause hemorrhagic fevers. World Health Organization director-general Tedros Adhanom Ghebreyesus confirmed the launch via a post on X, stating that if the drug is effective among high-risk contacts, this could mark a major step forward in preventing contacts from developing the disease.

Recruitment for the obeldesivir trial is taking place at PEP centers located next to Ebola treatment centers operated by the NGO The Alliance for International Medical Action (ALIMA) in Rwampara and Bunia, within the Ituri province. The study aims to recruit nearly 1,000 participants aged 12 and over who are not showing symptoms but were in direct contact with a confirmed case within the preceding five days. Participants will undergo daily monitoring for 21 days, with a final visit scheduled at 42 days.

Concurrent Treatment Research

While EBO-PEP targets those exposed, a separate international effort called the PARTNERS (Platform Adaptive Randomised Trial for New and Repurposed Filovirus TreatmentS) trial began patient enrollment on July 2, 2026. This trial assesses whether two therapies—the monoclonal antibody MBP134 and the antiviral remdesivir—can improve survival for those already diagnosed with BVD. Researchers are testing these treatments both alone and in combination.

Remdesivir, also known as Velkury, was the first approved antiviral for Covid-19. MBP134 is a double antibody-based therapy developed by Mapp Biopharmaceutical, utilizing antibodies isolated from a survivor of the 2013-2016 West African Ebola outbreak. According to Monica Gandhi, an infectious disease specialist and professor at the University of California, San Francisco, MBP134 targets binding sites common to multiple strains, including Sudan, Zaire, and Bundibugyo. Gandhi noted that a study in non-human primates showed a complete reverse of symptoms of a Sudan strain when MBP134 was administered.

The PARTNERS trial is a platform trial, allowing the WHO Technical Advisory Group to add new treatments as they become available. It is coordinated by the University of Oxford, the Institute of Tropical Medicine in Belgium, and the Institut National de Recherche Biomédicale (INRB) in the DRC, with support from Africa CDC.

Outbreak Severity and Response

The BVD outbreak was declared on May 15 after deaths occurred in the mineral-rich northeastern province of Ituri, an area plagued by armed groups. While cases have appeared in Uganda and five DRC provinces, more than 90 percent are detected in Ituri. Official DRC figures indicate more than 1,960 people have been infected and over 700 have died. Other reported figures state over 1,400 diagnosed cases, with nearly 440 deaths and nearly 210 recoveries in the DRC.

WHO emergencies chief Chikwe Ihekweazu warned in Geneva that the outbreak continues to outpace the response efforts. He reported that 80 percent of new cases were from unknown chains of transmission and were not on known contact lists. The WHO further cautioned that the outbreak could be two to four times larger than official figures suggest, noting that many victims die before reaching a health facility.

To combat the spread, the WHO has added the Ebola Virus (EBOV) Real Time RT-PCT Kit from Shanghai ZJ Bio-Tech Co to its Emergency Use Listing. Joint efforts with Africa CDC aim to expand laboratory testing capacity to over 2,000 tests per day. Additionally, the Coalition for Epidemic Preparedness Innovations (CEPI) previously awarded $60m to Moderna and two other groups to develop BVD vaccines.

Because no approved vaccines or treatments currently exist specifically for the Bundibugyo strain, the WHO previously declared the outbreak an international emergency. For now, patients receive supportive care, including oxygen support, electrolyte replacement, and blood pressure management. The PARTNERS trial will take several months to produce results and may run into next year, potentially requiring more than 1,000 patients for definitive answers.