Ebola Zaire vaccine (live, attenuated)

Ebola virus vaccine is a vaccine used to prevent Ebola virus disease caused by Zaire ebolavirus in adults, prevent outbreaks, and reduce the extent of the virus spreading in case of outbreaks.^L10854 Ebola virus disease, formerly known as Ebola hemorrhagic fever, is a rare but severe and often deadly disease. It is highly contagious: human to human transmission occurs from contact with body fluids from infected patients.^A189024 It is characterized by fever, headache, myalgia, and gastrointestinal symptoms. These may be accompanied by hypotension and respiratory, kidney and liver failure, as well as internal and external bleeding.A188994,A188997 In the Filoviridae family, there are five unique Ebolavirus species that are each named after the geographical region where it was first identified. The mortality rate of the Zaire species is about 80%.^A188997

Confirmed outbreaks of Ebola virus disease have been documented since the 1970s, mostly in Sub-Saharan Africa, where Ebola first appeared in 1976 near the Ebola River in Zaire (presently referred to as the Democratic Republic of the Congo) and Sudan.^A188994 Between 2014 and 2016, Ebola outbreaks occurred in West Africa, leading to more than 11,310 total deaths during this time in Guinea, Liberia, and Sierra Leone.^A188997 In 2016, this epidemic was exhausted after these countries were declared Ebola-free by 2016, and the World Health Organization (WHO) lifted the Public Health Emergency of International Concern (PHEIC) status on the West Africa Ebola outbreak.^L10884

The first live, attenuated Ebola virus vaccine was developed by a team of Canadian researchers at Canada’s National Microbiology Laboratory and was later patented by the Canadian government.^L10866 In non-human primate clinical trials, the vaccine was effective in inducing an immune response against the Ebola viruses.^A189018 This vaccine was later sold to NewLink Genetics, a biotech company that held the license to the vaccine from 2010 to 2014, although the vaccine was not marketed.^L10866 In 2014, Merck Inc. signed a licensing agreement with NewLink for further development and marketing. Ervebo, the marketed Ebola virus vaccine by Merck, was first approved by the European Commission in November 2019 after the European Medicines Agency recommended it be licensed. In December 2019, Ervebo was approved by the FDA in the United States. Ervebo consists of an envelope glycoprotein of the Zaire ebolavirus (Kikwit 1995 strain) fused into a vesicular stomatitis virus (VSV) backbone.^L10854 By introducing the relatively inactive viral protein to the patient, the patient’s immune system learns to recognize and attack the virus if he or she is exposed to it in the future.