U.S. buys additional 200 million doses of Pfizer vaccine

• The U.S. has now purchased 500 million of the 600 million possible doses negotiated between the Trump administration and Pfizer and BioNtech in July 2020.
• The purchase is separate from an agreement announced last month for Pfizer and BioNTech to provide the U.S. with 500 million vaccine doses to help vaccinate the world's poorest countries.

What they're saying: The 200 million doses the administration is exercising in its contract is to “prepare for future vaccination needs, including vaccines for children under 12 and possible booster shots if studies show they are necessary," according to a senior Biden administration official.

Between the lines: The announcement notes that the U.S. has the option to "acquire an updated version of the vaccine to address potential variants as well as new formulations of the vaccine, if available and authorized."

• Also as part of the agreement, Pfizer will provide the U.S. with 65 million pediatric doses should Pfizer’s vaccine be authorized for kids under 12.