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Preliminary Data Shows Two New Ebola Drugs Dramatically Decrease Mortality Rates

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Health workers beginning a shift in an Ebola outbreak zone in Beni, Democratic Republic of Congo, in July 2019.
Health workers beginning a shift in an Ebola outbreak zone in Beni, Democratic Republic of Congo, in July 2019.
Photo: Jerome Delay (AP)

Two new clinical treatments for the infamous Ebola virus may result in it becoming a “preventable and treatable” disease, the BBC reported on Monday, with a study of four drugs finding that two treatments called REGN-EB3 and mAb114 were effective in limiting mortality from the disease.

Per Wired, while researchers have already developed an experimental vaccine to prevent people from catching the virus, the two new treatments dramatically increase survival rates of individuals who have already contracted it. An international World Health Organization-coordinated team consisting of the Institut National de Recherche Biomedicale, the Democratic Republic of Congo Ministry of Health, and three humanitarian organizations began conducting trials in November 2018 and aimed to compare the effectiveness of new therapies on 725 patients. The study was carried out in regions of the DRC that have been experiencing the nation’s largest-ever Ebola outbreak, which began last year and has claimed nearly 1,900 lives.

Patients received either an antiviral drug called remdesivir or three drugs relying on monoclonal antibodies, which are large proteins that recognize specific pathogens and attract immune cells to destroy them, according to Wired. Two of the monoclonal antibody treatments, Regeneron’s REGN-EB3 and the U.S. National Institute of Allergy and Infectious Disease’s (NIAID) mAb114, proved so effective that the researchers halted the trial after enrolling just 681 patients of the 725 target. The BBC reported that use of Remdesivir and a third monoclonal antibody drug called ZMapp “have been dropped from trials as they were found to be less effective.”


Patients on ZMapp, an older treatment used in prior efforts to control Ebola outbreaks, had “an overall mortality rate of 49 percent,” compared to an overall mortality rate of over 75 percent in untreated patients, Wired wrote. The new drugs took that rate much lower, particularly when they were given to patients in the earlier stages of Ebola virus disease. Per Wired:

The monoclonal antibody cocktail produced by a company called Regeneron Pharmaceuticals had the biggest impact on lowering death rates, down to 29 percent, while NIAID’s monoclonal antibody, called mAb114, had a mortality rate of 34 percent. The results were most striking for patients who received treatments soon after becoming sick, when their viral loads were still low—death rates dropped to 11 percent with mAb114 and just 6 percent with Regeneron’s drug, compared with 24 percent with ZMapp and 33 percent with Remdesivir.


Preliminary findings from the study, based on data from 499 of the patients, were released on the National Institutes of Health website on Monday.

ZMapp relies on engineered antibodies originally produced by Ebola-infected mice, while REGN-EB3 is a cocktail of three types of monoclonal antibodies also generated in mice. mAb114 was developed by harvesting white blood cell DNA from an individual who survived an Ebola outbreak in DRC in 1995. According to Wired, further trials will now focus on whether REGN-EB3 or mAb114 are more effective, with the World Health Organization stating treatment centers in outbreak zones will now only administer the two most effective drugs.


“One thing that won’t change is that those two therapies are better than the other two—that’s for sure,” Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, told Science News.

Jeremy Farrar, director of the Wellcome Trust research charity, told the BBC that the treatments show Ebola is becoming a “preventable and treatable” disease, adding that “We won’t ever get rid of Ebola but we should be able to stop these outbreaks from turning into major national and regional epidemics.”