Ebola Bundibugyo in the DRC: vaccines and experimental treatments evaluated in an emergency.

Declared on May 15, 2026, the outbreak has accelerated the implementation of pre-prepared research. Trials are being conducted on patients with Ebola, and an oral medication is being offered to certain contacts considered to be at high risk after possible exposure.

The first vaccine candidate, developed by the University of Oxford and the Serum Institute of India, entered phase I on July 24 in the UK. The second, developed by Moderna, is being tested in Canada following an authorization issued by Health Canada on July 30, with about 80 healthy adults expected to participate in the study.

These early trials are not yet aiming to prove that the vaccines prevent the disease. They must first measure their safety, determine the appropriate dosage, and check the ability of the products to trigger an immune response against the Bundibugyo virus, without exposing volunteers to the virus.

Treatments Evaluated on Patients

According to the World Health Organization, it will take several months before the first data on the two vaccines are available. Later phase trials, conducted on larger groups, would then be necessary before any potential authorization requests.

In the DRC, a therapeutic trial supported by the WHO is being conducted in several care centers in Ituri, the main hub of the outbreak. More than 50 patients with a confirmed diagnosis had been included by August 4, across three centers, while a fourth was expected to begin recruiting that week.

The objective is to gradually expand the study to at least ten facilities. The names and compositions of the evaluated treatments have not been specified, preventing any assessment of their effectiveness or potential impact on mortality.

The main difficulty faced by researchers seems to be not the patients’ refusal, but the limited number of centers capable of implementing the protocol. It is necessary to quickly confirm the diagnosis, have trained personnel, and ensure medical follow-up as well as data collection.

Late arrivals in care facilities also complicate recruitment. As of August 3, 30 of the 44 confirmed deaths recorded in the previous 24 hours had occurred in the community and were established through post-mortem samples, compared to 14 deaths in Ebola treatment centers.

A Medication Proposed After Risk Exposure

Another study, conducted by the National Institute of Biomedical Research of the DRC with international partners, focuses on an oral medication administered over ten days to high-risk contacts. Researchers want to determine if this treatment can prevent the onset of the disease or reduce the risk of developing it after contact with the virus.

More than 25 people had received the product according to information provided by the WHO. In Tshopo province, two high-risk contacts among frontline staff were particularly receiving experimental treatment in Madula, one of whom had completed their follow-up.

The treatment of a hospital contact from the Cinquantenaire Hospital in Kisangani had been interrupted. In Kongakonga, eight high-risk contacts refused the proposed treatment, with neither the reasons for these refusals nor the name of the medication specified.

The success of this trial depends on the rapid identification of contacts, the assessment of their level of exposure, their consent, and their follow-up throughout the treatment duration. As of August 3, 18,243 contacts were recorded across the five affected provinces, but only 14,300 had been seen, which is 78.4%, a rate lower than the operational goal of 95%.

An Outbreak Still Actively Ongoing

Follow-up varied significantly by province. It reached 80.2% in Ituri, 76% in North Kivu, 63% in Haut-Uele, 81.7% in Tshopo, and 100% in South Kivu, with discrepancies likely to delay the identification of individuals who could participate in the post-exposure trial.

The WHO is also examining new data obtained from animal studies on Ervebo, the vaccine already used against the Zaire Ebola virus. This product was not designed against the Bundibugyo virus, and no definitive conclusion currently allows for asserting that it provides protection against this variant.

As of August 3, Congolese authorities reported 3,874 confirmed cases, 1,751 deaths, and 749 recoveries, resulting in a fatality rate of 45.1%. The outbreak affected 51 health zones in five provinces, with a marked concentration in Ituri, which accounted for 3,375 cases, or 87.1% of the total.

North Kivu had 426 cases, Haut-Uele 63, Tshopo seven, and South Kivu three. Transmission remained sustained, fueled in particular by population movements, insecurity, artisanal mining activities, and exchanges with Uganda and South Sudan.

Care Capacities Under Pressure

A total of 717 patients were in isolation, including 471 in Ituri and 196 in North Kivu. In the latter province, authorities reported 196 isolated patients for 141 available beds.

The Oicha center, equipped with ten beds, was fully occupied and faced a lack of protective equipment. These tensions limit the possibility of opening new trial sites and ensuring sufficient conditions to protect both patients and caregivers.

The Congolese report mentions 11 protocols approved by the ethics committee in Ituri. Three studies had been completed, three reports produced, and one publication made available, while four out of 22 recommendations had been implemented.

Investigators had also been deployed with the support of the African Centres for Disease Control and Prevention. A qualitative study was being prepared in the health areas of Bunia and Rwampara to better understand the hesitancies regarding transfers, post-mortem samples, and certain experimental treatments.

At this stage, no results allow asserting that a vaccine prevents the disease, that a treatment reduces mortality, or that the medication administered after exposure prevents infection. The response continues to rely on the rapid detection of cases, their isolation, supportive care, contact tracing, infection prevention, and dignified and safe burials.