World Health Organization Backs Adding Two New Vaccines to an Ongoing Ebola Trial

The World Health Organization said on November 4 that expert advisers have recommended adding two new vaccine candidates to an Ebola trial already running in the Democratic Republic of Congo. The vaccines will join the study only after each country involved gives its own approval, so this is a step toward testing them, not a finished rollout.

The two shots were built for the strain behind the current outbreak, known as Bundibugyo. One, called ChAdOx1, comes from the University of Oxford and the Serum Institute of India. The other, mRNA-1469, was developed by the drugmaker Moderna. The World Health Organization says this will be the first time vaccines designed for the Bundibugyo strain are tested during an outbreak of it.

They will be added to a study named Tumaini, which means hope in Swahili. The trial uses a ring approach that vaccinates people who have been in close contact with confirmed patients, a method meant to break the chain of spread. It builds on work from the West Africa Ebola outbreak a decade ago. The country's National Institute for Biomedical Research is leading the study, with support from the World Health Organization and partner groups.

The outbreak has been severe. The European Centre for Disease Prevention and Control, citing figures reported by Congo's health ministry, said that as of early November there were 10,532 confirmed cases and 5,126 related deaths, based on data through November 1. That means nearly half of confirmed patients have died, though officials caution that the numbers are still under review as cases are confirmed and sorted.

The new candidates will join a vaccine that is already being evaluated inside Tumaini. That first shot, called Ervebo, is approved to protect against a different form of Ebola known as the Zaire strain. It has not been proven to work against Bundibugyo, but the trial is testing whether it offers any cross-protection against the strain driving this outbreak. Because no vaccine is yet proven against Bundibugyo, the two new candidates are being added to the same study.

Results from the vaccine trial are expected in early 2027, with early findings from treatment studies due sooner. The World Health Organization stresses that vaccines alone will not end the outbreak, and that steady work such as early care, contact tracing, and trust with local communities remains essential.