Conflict growing between US and allies over vaccine supply

Police officers and wait in a line to receive their COVID-19 vaccine at the Brussels Expo center in Brussels, Thursday, March 4, 2021. The Expo is one of the largest vaccination centers in Belgium. (AP Photo/Olivier Matthys)

President Joe Biden passes a note to Secretary of State Antony Blinken, during a virtual meeting with Indian Prime Minister Narendra Modi, Australian Prime Minister Scott Morrison and Japanese Prime Minister Yoshihide Suga, from the State Dining Room of the White House, Friday, March 12, 2021, in Washington. (AP Photo/Alex Brandon)

A healthcare worker administers a dose of the AstraZeneca COVID-19 vaccine to a woman at the Brussels Expo center in Brussels, Thursday, March 4, 2021. The Expo is one of the largest vaccination centers in Belgium. (AP Photo/Olivier Matthys)

WASHINGTON — President Joe Biden’s administration is stockpiling tens of millions of doses of a COVID-19 vaccine whose approval in the U.S. remains uncertain, frustrating U.S. allies who say those doses should be used now to save lives overseas.