The United States will distribute half a billion Pfizer vaccines to 100 other countries.
Some 200 million doses will be distributed this year and 300 million in 2022.
It comes as US President Joe Biden said before leaving for the G7 summit in Cornwall that he would announce a vaccination strategy for the world.
The United States would pay for the doses at a “not-for-profit” price, according to the New York Times, which said the plan could be officially announced on Thursday.
America is well advanced in rolling out its vaccines, but campaigners have called on rich countries to do more to help protect developing countries.
The World Health Organization’s Covax program aims to address what some have called “vaccine apartheid” by working with governments and manufacturers to ensure equitable distribution of COVID vaccines.
It aims to deliver two billion doses in 2021 and 1.8 billion doses to 92 low-income economies by early 2022.
It is not yet clear whether America will distribute Pfizer’s 500 million jobs fully or partially through Covax.