More than 2,800 people have been infected with the Ebola virus during the ongoing outbreak in the Democratic Republic of the Congo.Credit: Jerome Delay/AP/Shutterstock

Two Ebola drugs have proven so effective in a clinical trial that researchers will make the treatments available to anyone infected with the virus in the Democratic Republic of the Congo (DRC), where Ebola has killed nearly 1,900 people over the past year.

The survival rate for people who received either drug shortly after infection, when levels of the virus in their blood were low, was 90%.

“It’s really good news,” says Sabue Mulangu, an infectious-disease researcher at the National Institute for Biomedical Research (INRB) in Kinshasa in the DRC, and an investigator on the trial. “Now we will be able to stress to people that more than 90% of people survive if they come into the [Ebola treatment unit] early and get this treatment.”

One of the drugs, REGN-EB3, is a cocktail of three monoclonal antibodies against Ebola made by Regeneron Pharmaceuticals of Tarrytown, New York. The second, mAB114, is derived from a single antibody recovered from the blood of a person who survived Ebola in the DRC in 1995 , and was developed by the US National Institute of Allergy and Infectious Diseases (NIAID).

Both drugs outperformed two other experimental treatments in the unprecedented multi-drug clinical trial in the DRC, the World Health Organization, INRB and NIAID said in a joint statement on 12 August. Preliminary data from the first 499 people enrolled in the study show that 29% of people given REGN-EB3 died, compared with 34% of those who received mAb114.

By contrast, 53% of patients who received the anti-viral drug remdesivir died, as did 49% of those who received ZMapp, an antibody treatment that was tested during a major Ebola outbreak in West Africa from 2014 to 2016.

Jean-Jacques Muyembe Tamfum, the director-general of the INRB and a co-discoverer of Ebola, says he hopes the results inspire people to bring their sick loved ones to Ebola clinics for treatment. According to the WHO, people are waiting an average of 5-6 days after they notice the first symptoms of infection to seek treatment at an Ebola centre.

The outbreak in the eastern DRC is the second-worst ever; more than 2,800 people have been infected with Ebola, including the nearly 1,900 who have died. Distrust and violence in the area have hampered efforts to halt the virus’s spread.

The drug trial, which launched last November, has a unique design that allows it to stop and restart if attacks near Ebola centres impede treatment, or if the outbreak ends. Researchers will continue to collect trial data on REGN-EB3 and mAB114, in the hopes of seeking regulatory approval.

“I’m in awe about what seemed to be an impossible clinical trial to run,” says Sumathi Sivapalasingam, a senior director at Regeneron. “The team did this in such a complex emergency and still, the data quality is exceptional.”