Drug Trial Aims to Prevent Ebola Infection in Congo Outbreak

More than 250 participants have enrolled in a trial for a drug that could prevent Ebola infection in Congo, marking a critical step in combating the deadliest outbreak of the disease in the Central African country. The drug, Gilead's experimental antiviral pill obeldesivir, is targeted at the Bundibugyo virus, which is responsible for the current fast-moving outbreak and lacks an approved vaccine or treatment.

The trial, named EBO-PEP, began in July and is one of several studies aiming to find protection against or slow the spread of the virus. The study is being conducted in the eastern province of Ituri, the epicenter of the outbreak.

Participants include individuals exposed to the disease, such as health workers and relatives of patients. The experimental drug is administered soon after suspected contact with the virus to prevent it from developing, a method known as post-exposure prophylaxis (PEP). Participants are monitored daily for 21 days, with a final check-in after 42 days.

One participant, who enrolled after her husband tested positive for Ebola, reported that no family members had developed symptoms so far. Another participant, who lost a family member to the disease, stated, “This disease is killing. It’s better to take precautions.” Participants have requested anonymity to protect their privacy.

Ebola disease only becomes transmissible once symptoms appear. Identifying and tracking individuals at high risk of incubating the Bundibugyo virus, through contact tracing, has proven challenging in Congo.

The trial, coordinated by the medical nonprofit ALIMA, aims to recruit nearly 1,000 adults and children over 12 who have had contact with a confirmed case within the last five days but show no symptoms. Half of the participants will receive a placebo.

If trial participants develop symptoms, they will immediately receive supportive treatment, which has shown effectiveness when initiated early. According to ALIMA research coordinator Dr. Guilavogui Jean Paul Yassa, the drug differs from a vaccine in that it is intended for individuals not yet showing symptoms, and from curative treatment as it is preventative.

Dr. Jacques Zawadi, an investigating physician with ALIMA, noted that while most participants are willing to join the study, encouraging those living far from the trial center has been difficult. He also highlighted the emotional toll on participants when family members die from the disease, which can disrupt their engagement with the study.

Partners in the trial include Congo’s National Institute of Biomedical Research and France's ANRS Emerging Infectious Diseases. The trial is also supported by the National Institute of Allergy and Infectious Diseases.

This outbreak has recorded at least 8,300 confirmed cases and over 4,000 deaths since it was declared in mid-May. The disease has spread to seven provinces and continues to outpace containment efforts. The World Health Organization has indicated the outbreak may exceed the 2014-2016 West Africa outbreak, which was the deadliest on record with 11,000 deaths.

Congo has also been vaccinating health workers with the Ervebo vaccine, which was effective in previous outbreaks caused by a different Ebola virus strain. Authorities suggest Ervebo may offer some protection against Bundibugyo, though its efficacy is still under study. Separately, a Doctors Without Borders staff member recently tested positive and was evacuated for treatment, and an ALIMA physician tested positive after returning to France from a virus hotspot in June.