Over 5,000 people have been infected with the Ebola Bundibugyo virus in the Democratic Republic of Congo (DRC), but the outbreak may be three times the officially reported size, warned the Africa Centre for Disease Control and Prevention has said.

Speaking at a press briefing, Africa CDC’s Prof Yap Boum said the estimation of various experts and academics, is that “only 30-40% of cases” are in fact being detected and reported.

Part of the reason is that the symptoms for Bundibugyo are milder than Ebola Zaire and “you don’t have the bleeding”, which makes it harder to distinguish from other illnesses, he added.

Boum also noted that the vast majority of deaths – 97% in the past week – were still taking place in the “community” – although he clarified that the definition includes health facilities that were not Ebola treatment centres.

Once again, the Africa CDC highlighted the weakness in contact tracing, with only around 16% of contacts with confirmed Ebola cases having been traced.

Spread to DRC regions near Central African Republic an emerging concern

Boum also sounded the alarm about new cases detected in the DRC provinces of Haut-Uélé and Bas-Uélé, which border the Central African Republic (CAR). Two cases have now been detected in the Bas-Uélé capital of Buta, about 200km from the CAR border.

Last week, the World Health Organization (WHO) Director-General Dr Tedros Adhanom Ghebreyesus and Africa CDC leaders met in CAR, which has also been wracked by years of conflict, to assist the country to prepare for Ebola in case it moved across the border.

Measures include increased surveillance at checkpoints and borders, and bolstering laboratories.

Ervebo vaccines to be trialled in DRC against Bundibugyo virus strain

Meanwhile, the DRC and international partners as preparing to conduct a clinical trial testing the efficacy of the Ervebo vaccine against the Zaire ebolavirus strain against Bundibugyo in amongst groups of health workers deemed to be at highest risk, WHO said on Thursday.

This followed an agreement with the International Coordinating Group on Vaccine Provision (ICG) to send 70,000 doses of Ervebo vaccines to the DRC, at the government’s. The ICG manages the vaccine stockpile in partnership with WHO, the International Federation of the Red Cross and Red Crescent, Médecins Sans Frontières and UNICEF. Gavi, the Vaccine Alliance, provides funding for the stockpile.

I welcome the decision by the International Coordinating Group on Vaccine Provision to release an initial 70,000 doses of the Ervebo vaccine to the Democratic Republic of the Congo. Of these, 20,000 doses will support a Phase 3 clinical trial to better understand the vaccine’s… https://t.co/HG8KR4gDNB

— Tedros Adhanom Ghebreyesus (@DrTedros) August 20, 2026

While Ervebo is only licensed and recommended for use against the Zaire ebolavirus strain, early laboratory and animal data suggest it may provide some protection, WHO said.

The allocation includes 20,000 doses for the Phase 3 of this trial, and 50,000 doses are for frontline health workers, in line with the current recommendations of the WHO Strategic Advisory Group of Experts on Immunization (SAGE).

Two other vaccine candidates, ChAdOx1, and Moderna’s mRNA vaccine, are currently recruiting patients in the DRC for early trials.

Image Credits: John Wessels/ MSF.