The World Health Organization announced Tuesday that the first four participants have received doses in a new clinical trial launched in the Democratic Republic of Congo to determine whether an existing Ebola vaccine can reduce severe illness and deaths caused by the Bundibugyo virus.

TUMAINI trial launches

WHO Director of Science for Health Meg Doherty told reporters in Geneva that the study, named TUMAINI — meaning hope in Swahili — began on Friday. Researchers are examining whether Ervebo, a vaccine known to be effective against the Zaire Ebola virus, can reduce severe disease and death from the Bundibugyo strain rather than prevent infection entirely.

Ring-vaccination approach

Investigators are employing a ring-vaccination strategy that involves immunizing people who have been in close contact with confirmed Ebola patients or otherwise exposed to the virus. Two vaccination rings have already been established, with several more being prepared, Doherty noted.

Eligible participants can receive the vaccine between one and 21 days after exposure, although scientists have not yet determined whether timing affects outcomes. “We do not yet know for certain when results will begin to emerge. We expect it will take several months,” Doherty said.

Multiple candidates under review

The trial is led by Congolese researchers and managed by the country’s National Institute for Biomedical Research, with support from WHO and international partners. Designed as a platform trial, TUMAINI can evaluate multiple vaccine candidates within a single research framework.

WHO advisory groups reviewed two vaccines developed specifically against the Bundibugyo virus last week: ChAdOx1, developed by the University of Oxford with the Serum Institute of India, and Moderna’s mRNA-1469. Recommendations on those vaccines are expected this week, the science director stated.

Community response

Doherty noted that community members were already approaching the trial site seeking to enroll, underscoring the urgent need for an effective vaccine against the Bundibugyo virus. The approach builds on the ring-vaccination strategy used during the West African Ebola outbreak a decade ago, which helped establish Ervebo’s effectiveness against the Zaire virus.