The US government is considering giving some people half the dose of Moderna's Covid-19 vaccine in order to speed vaccinations, a federal official said on Sunday.

Moncef Slaoui, head of Operation Warp Speed, the federal vaccine program, said on CBS' "Face the Nation" that officials were in talks with Moderna and the Food and Drug Administration about the idea. Moderna's vaccine requires two injections. "We know that for the Moderna vaccine, giving half of the dose to people between the ages of 18 and 55, two doses, half the dose, which means exactly achieving the objective of immunizing double the number of people with the doses we have," Slaoui said.