The Food and Drug Administration has approved its first-ever vaccine against a form of the Ebola virus, several months ahead of schedule.

The FDA said Thursday that it had approved Kenilworth, New Jersey-based Merck & Co.’s Ervebo, a vaccine against the Zaire ebolavirus to prevent Ebola virus disease, or EVD. The agency had accepted Merck’s regulatory submission for the vaccine in September, setting a March 14, 2020 action date for deciding whether or not to approve it. The European Medicines Agency approved the vaccine last month, and Ervebo had previously been granted access for emergency use.

“Approval of this vaccine by the FDA represents another important milestone in the global response to Ebola virus disease and stands as a tremendous accomplishment by a unique global partnership,” Merck Research Laboratories President Roger Perlmutter said in a statement. “In acknowledgment of this event, I wish in particular to recognize the heroic efforts being made by frontline responders to the ongoing outbreak in the Democratic Republic of the Congo.”

Data from a Phase III study showed that immune responses to the vaccine persisted for two years, while the vaccine itself was well-tolerated among patients.

The approval comes at a time when the Democratic Republic of the Congo faces the second largest Ebola epidemic on record. As of Wednesday, there were 3,351 cases and 2,211 deaths, while 1,089 people had survived, according to the World Health Organization. The largest Ebola outbreak in history occurred in West Africa in 2014, with 28,610 cases and 11,308 deaths reported in Guinea, Liberia and Sierra Leone, according to the Centers for Disease Control and Prevention. Death rates in outbreaks have ranged from 25-90%. The virus was discovered in 1976.

Ervebo is not the first Ebola vaccine to win regulatory approval globally. Two others, the Russian vaccine GamEvac-Combi and the Chinese-developed Ad5-EBOV, have been licensed in their respective countries of origin.

“While the risk of Ebola virus disease in the U.S. remains low, the U.S. government remains deeply committed to fighting devastating Ebola outbreaks in Africa, including the current outbreak in the Democratic Republic of the Congo,” FDA Deputy Commissioner for Policy, Legislation and International Affairs Anna Abram said in a statement.

Photo: Cooper Neill, Getty Images