The World Health Organization (WHO) approved clinical trials for two new Ebola vaccines on Wednesday, as an outbreak in Africa has killed more than 5,300 people.

The candidates are ChAdOx1 BDBV, developed by the University of Oxford with the Serum Institute of India, and Moderna’s mRNA-1469, both designed specifically for the Bundibugyo virus. WHO Director-General Tedros Adhanom Ghebreyesus said the trial that began last month with the Ervebo vaccine does not cover the Bundibugyo virus and that the agency’s expert groups now recommend adding the two candidates to the study. The National Institute for Biomedical Research of the Democratic Republic of Congo (DRC) leads the trial, backed by partners including WHO. The Africa Centres for Disease Control and Prevention (Africa CDC) said on Monday that the epidemic had killed more than 5,300 people, the majority in the DRC, with 10,444 confirmed cases and a fatality rate above 50 percent.