Western African Ebola virus epidemic

The Western African Ebola virus epidemic (2013–2016) was the most widespread outbreak of Ebola virus disease (EVD) in history, causing major loss of life and socioeconomic disruption in the region, mainly in Guinea, Liberia and Sierra Leone. The first cases were recorded in Guinea in December 2013; later, the disease spread to neighbouring Liberia and Sierra Leone, with minor outbreaks occurring elsewhere. It caused significant mortality, with the case fatality rate reported which was initially considerable,   while the rate among hospitalised patients was 57–59%, the final numbers 28,616 people, including 11,310 deaths, for a case-fatality rate of 40%. Small outbreaks occurred in Nigeria and Mali, and secondary infections of medical workers occurred in the United States and Spain. In addition, isolated cases were recorded in Senegal, the United Kingdom and Italy. The number of cases peaked in October 2014 and then began to decline gradually, following the commitment of substantial international resources. , the World Health Organization (WHO) and respective governments reported a total of 28,646 suspected cases and 11,323 deaths (39.5%), though the WHO believes that this substantially understates the magnitude of the outbreak.

On 8 August 2014, a Public Health Emergency of International Concern was declared and on 29 March 2016, the WHO terminated the Public Health Emergency of International Concern status of the outbreak. Subsequent flare-ups occurred; the epidemic was finally declared over on 9 June 2016, 42 days after the last case tested negative on 28 April 2016 in Monrovia.

The outbreak left about 17,000 survivors of the disease, many of whom report post-recovery symptoms termed post-Ebola syndrome, often severe enough to require medical care for months or even years. An additional cause for concern is the apparent ability of the virus to "hide" in a recovered survivor's body for an extended period of time and then become active months or years later, either in the same individual or in a sexual partner. In December 2016, the WHO announced that a two-year trial of the rVSV-ZEBOV vaccine appeared to offer protection from the variant of EBOV responsible for the Western Africa outbreak. The vaccine is considered to be effective and is the only prophylactic which offers protection; hence, 300,000 doses have been stockpiled. rVSV-ZEBOV received regulatory approval in 2019.