On Wednesday, Pfizer and BioNTech announced having reached a deal with the U.S. government with an additional 100 million doses by July 31.
That's up from the initial 100 million doses ordered already.
The deal follows a similar extension of doses reached by the U.S. with Moderna for their vaccine.
Both vaccines require two doses to be administered.
The $2 billion deal calls for at least an additional 70 million doses to be provided to the U.S. by June 30.
