The U.S. plans to buy 500 million doses of Pfizer Inc.’s coronavirus vaccine to share internationally as President Joe Biden prepares to join other Group of Seven leaders in a campaign to end the pandemic by distributing shots worldwide.

As Biden and other G7 leaders gather for the start of their summit in the U.K., their staffs have been putting together a document that outlines a plan to end the COVID-19 pandemic by December 2022. At the summit in Cornwall, the presidents and prime ministers will pledge to deliver at least 1 billion extra doses of vaccines over the next year to help cover 80% of the world’s adult population, according to a draft communique.

The U.S. government will buy about 200 million doses this year to distribute through COVAX, the World Health Organization-backed initiative aimed at securing an equitable global distribution of the vaccine, and about 300 million doses in the first half of next year, a person familiar with the matter said.