These Experimental Ebola Treatments and Vaccines Might Help Slow the Outbreak Spreading in the Congo and Uganda, WHO Says

No approved therapeutics exist for the virus species causing the outbreak, which has been associated with more than 1,000 cases of Ebola. The World Health Organization has identified several therapeutics to test in clinical trials in the coming months

Sara Hashemi | Daily Correspondent

June 2, 2026 12:11 p.m.

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Ebola is currently wreaking havoc in the Democratic Republic of the Congo (DRC) and Uganda. More than 1,000 confirmed or suspected cases of the rare but severe disease, including more than 200 deaths, have been reported from the two countries as of late May, according to the World Health Organization (WHO).

The current outbreak is caused by the Bundibugyo virus, a rare species for which there are no approved vaccines or treatments. On May 28, the WHO announced a slew of experimental therapeutics for Ebola that experts recommend for priority testing to slow the spread of the deadly disease. The global agency will work with the DRC and Uganda’s governments to research the products, which include candidate vaccines and repurposed treatments for Covid-19.   

Among them is obeldesivir, a pill developed by the California-based pharmaceutical company Gilead Sciences. It was originally created for Covid-19, although it is not currently approved for that use in the United States. The WHO identified this drug as a possible way to prevent disease after exposure to the Bundibugyo virus, and researchers are preparing to launch a trial in the countries affected by the outbreak.

“Since we don’t have vaccines, this is something you can do immediately that could be effective,” says Ira Longini, a biostatistician at the University of Florida, to Kai Kupferschmidt at Science.

Obeldesivir has shown promising results in animals against two other Ebola-causing viral strains, called the Zaire and Sudan viruses. The drug prevented death in 80 to 100 percent of monkeys when taken 24 hours after they were injected with the strains, reports Science.

However, researchers don’t know whether the drug would ​be effective in people showing symptoms of Ebola, and it hasn’t been evaluated for the Bundibugyo virus, says Thomas Geisbert, a virologist at the University of Texas Medical Branch who has researched obeldesivir, to Julie Steenhuysen at Reuters.

Still, obeldesivir was found to be generally safe in a late-stage clinical trial involving nearly 2,000 participants with mild Covid-19. “I think that that’s something that potentially has ‌some utility” for the current Ebola outbreak, Geisbert adds.

The WHO notes that the success of this approach, called post-exposure prophylaxis, will depend on effective contact tracing, which can be difficult in some parts of the DRC. For decades, the country has been facing a complex displacement crisis due to ongoing conflict, instability, epidemics and climate issues. The nation has a “very mobile population,” Siouxsie Wiles, a microbiologist at the University of Auckland in New Zealand, told Nature’s Rachel Fieldhouse and Mohana Basu earlier this month.

Additional possible prevention measures include two candidate vaccines and Ervebo, the only licensed Ebola vaccine, although it is not currently greenlit for Bundibugyo virus because of limited evidence of its effectiveness against it. The candidate deemed most promising by experts, the single-dose rVSV Bundibugyo vaccine, will likely be ready for clinical trials in seven to nine months, per the WHO. The other candidate, ChAdOx1 Bundibugyo, could be ready in two to three months, though the agency says more animal testing is still needed.

The WHO also recommends priority testing of several potential treatments for Bundibugyo-caused Ebola. One of them contains two types of disease-fighting antibodies isolated from the blood of an Ebola survivor. Called MBP134 and developed by California-based Mapp Biopharmaceutical, this drug is designed to target all species of Ebola virus.

So far, it has helped ferrets and monkeys in the lab survive infections with multiple Ebola-causing viral strains, including Bundibugyo. “This is by far the strongest preclinical data for any of the treatments or therapies,” Geisbert told Science’s Kupferschmidt before the WHO’s announcement.

Another highlighted experimental treatment, remdesivir—approved as a Covid-19 treatment by the U.S. Food and Drug Administration—has shown mixed results for Ebola, per the outlet, although some research hints it might help patients if given early enough after infection.

Sara Hashemi | Read More

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.