The U.S. government said Thursday it will purchase and donate 500 million doses of Pfizer Inc.'s coronavirus vaccine to more than 90 lower-income countries and the African Union, an announcement that came just ahead of the Group of Seven summit meeting in Britain.The United States hopes the move will spur a coordinated vaccination effort via cooperation between the world's wealthy democracies, the White House said, apparently in a bid to counter so-called vaccine diplomacy by China and Russia, which it has labeled as autocracies.The vaccines, developed by the U.S. pharmaceutical giant and i…READ FULL ARTICLE