The US Food and Drug Administration has approved an Ebola vaccine for the first time. The vaccine, Ervebo, is produced by Merck & Co. and was tested during a recent outbreak in West Africa. It has been administered more than 223,000 times during the current outbreak in the Democratic Republic of the Congo, where it is being used on an experimental basis. Ervebo is made from a live but weakened virus engineered to express an Ebola protein. The European Commission previously approved the vaccine.