DR Congo launches Ervebo trial against Bundibugyo Ebola

New clinical trials for the Ervebo Ebola vaccine have begun in the Democratic Republic of Congo, the first time the drug will be tested against the Bundibugyo strain that is driving the current outbreak. The study, coordinated by the World Health Organization and the Congolese Ministry of Health, will roll out in three provinces that have reported the highest numbers of cases since the outbreak began in early 2024.

The Bundibugyo virus, first identified in Uganda in 2007, is a distinct lineage of the Zaire ebolavirus group. It has caused smaller, less lethal outbreaks in the past, but the current surge in the eastern provinces has raised alarms because the strain’s transmission dynamics differ from the Zaire strain for which Ervebo received emergency use authorization in 2019. Health officials say that the existing vaccine’s effectiveness against Bundibugyo is unproven, and a targeted study is needed to determine whether the immune response it induces can protect against this newer variant.

The trial will enroll around 3,000 participants across health facilities in North Kivu, Ituri, and South Kivu. Participants will receive the standard single-dose Ervebo regimen, and researchers will monitor antibody levels and any subsequent infections for 12 months. The study is expected to begin in late September, with interim safety data to be reviewed by an independent data monitoring committee. The WHO’s Director-General, Dr. Tedros Adhanom Ghebreyesus, has said that the trial is “a critical step to ensure that our vaccine arsenal remains effective as the virus evolves.” Local health workers have expressed cautious optimism, noting that early vaccination could curb the spread in remote villages where access to care is limited.

If the vaccine proves effective against Bundibugyo, the results could prompt a rapid rollout across the outbreak zone and inform future vaccine development strategies. The data will also be shared with global partners to assess whether cross-protection is sufficient for broader use in regions where multiple Ebola lineages circulate. The trial’s outcome will shape policy decisions about stockpiling, emergency deployment, and the design of next‑generation vaccines that target a wider spectrum of ebolavirus strains.