The agreement also would allow the federal government to acquire an additional 500 million doses of the Pfizer vaccine.

Pfizer Inc. headquarters stands in New York, U.S., on Wednesday, July 22, 2020. U.S. health officials agreed pay $1.95 billion for 100 million doses of a vaccine made by Pfizer Inc. and BioNTech SE, the latest step in an effort to fight the coronavirus pandemic. Photographer: Jeenah Moon/Bloomberg via Getty Images