The U.S. will begin sharing its entire stock of AstraZeneca COVID-19 vaccines with the world once it clears federal safety reviews, the White House said Monday, with as many as 60 million doses expected to be available for export in the coming months. The move greatly expands on the Biden administration’s action last month to share about 4 million doses of the vaccine with Mexico and Canada. The AstraZeneca vaccine is widely in use around the world but has not yet been authorized by the U.S. FDA.