The United Sates will provide 500 million doses of the Pfizer Covid-19 vaccine to about 100 countries over the next two years.
About 200 million doses will be distributed this year, with the remainder to be delivered in 2022.
The US has been under pressure to raise vaccination rates in poor countries.
The White House is yet to officially comment on the plan to roll out 500 million doses worldwide.
But when asked if the US government had a vaccination strategy for the world President Joe Biden said he has one, and will shortly be announcing it.
The US government will donate the vaccines to 92 lower-income countries and the African Union.
Distribution will go through the Covax scheme, which was set up last year to try to ensure fair access to vaccines among rich and poor nations.