FILE - In this July 13, 2019 file photo, health workers wearing protective suits tend to an Ebola victim kept in an isolation cube in Beni, Congo. According to a report published in the New England Journal of Medicine on Wednesday, March 31, 2021, an African man who developed Ebola despite receiving a vaccine recovered, but he suffered a relapse nearly six months later that led to 91 new cases before he died. The report adds to evidence that the deadly virus can lurk in the body long after symptoms end, and that survivors need monitoring for their own welfare and to prevent spread. (AP Photo/Jerome Delay, File)

FILE - In this Saturday, July 13, 2019 file photo, a person is vaccinated against Ebola in Beni, Congo. According to a report published in the New England Journal of Medicine on Wednesday, March 31, 2021, an African man who developed Ebola despite receiving a vaccine recovered, but he suffered a relapse nearly six months later that led to 91 new cases before he died. The report adds to evidence that the deadly virus can lurk in the body long after symptoms end, and that survivors need monitoring for their own welfare and to prevent spread. (AP Photo/Jerome Delay, File)