As many as 60 million doses are expected to be available for export in the coming months.
The move, announced on Monday (Tuesday AEST), greatly expands on the Biden administration’s action last month to share about 4 million doses of the vaccine with Mexico and Canada.
The AstraZeneca vaccine is widely in use around the world but has not yet been authorised by the US Food and Drug Administration.
The White House is increasingly assured about the supply of the three vaccines its healthcare workers are administering, particularly following the restart of the single-dose Johnson & Johnson shot over the weekend.
“Given the strong portfolio of vaccines that the US already has and that have been authorised by the FDA, and given that the AstraZeneca vaccine is not authorized for use in the US, we do not need to use the AstraZeneca vaccine here during the next several months,” White House COVID-19 coordinator Jeff Zients said.
“Therefore the US is looking at options to share the AstraZeneca doses with other countries as they become available.”
More than 3 million people worldwide have died of COVID-19, including more than 572,000 in the US.
The US has vaccinated more than 53 per cent of its adult population with at least one dose of its three authorized vaccines and it expects to have enough supply for its entire population by early summer.
About 10 million doses of AstraZeneca vaccine had been produced but were yet to pass review by the FDA to “meet its expectations for product quality,” Mr Zients said, noting the regulator was recognized as the “gold standard” for safety around the world.
That process could be completed in the next several weeks. About 50 million more doses are in various stages of production and could be available to ship in May and June pending FDA sign-off.
The US was yet to finalise where the AstraZeneca doses would go, the coordinator said.
Neighbours Mexico and Canada have asked the Biden administration to share more doses, while dozens of other countries are looking to access supplies of the vaccine.
The US government, which has contracted with AstraZeneca for a total of 300 million doses, will donate the doses — though the company has faced production issues.