The U.S. government had the option to buy 500 million additional doses of the Pfizer-BioNTech Covid-19 vaccine, but sources say that so far there are no plans to purchase additional doses.
The U.S. government had the option to buy 500 million additional doses of the Pfizer-BioNTech Covid-19 vaccine, but sources say that so far there are no plans to purchase additional doses.