The Biden administration intends to join the COVAX vaccine facility - which aims to deliver coronavirus vaccines to poor countries.
President Joe Biden's chief medical adviser, Anthony Fauci spoke to the World Health Organization from Washington on Thursday (January 21) - a day after the inauguration.
He also confirmed that the United States would remain a member of the U.N. agency.
"I am also pleased to announce today that the United States plans to work multilaterally to respond to and recover from the COVID-19 pandemic. President Biden will issue a directive later today, which will include the intent of the United States to join COVAX and support the ACT-Accelerator to advance multilateral efforts for COVID-19 vaccine, therapeutic, and diagnostic distribution, equitable access, and research and development."
WHO head Tedros Adhanom Ghebreyesus welcomed the decision.
"This is good day for WHO and a good day for global health. The role of the United States, its global role, is very, very crucial, and I send my deep thanks and warm congratulations to President Biden and Vice-President Harris and to the American people."
WHO officials said earlier this week that the first coronavirus batches are expected to go out to poorer countries in February under the COVAX scheme.
But they also raised concerns that richer countries are still grabbing the lion's share of available shots.
Fauci also said the United States will, quote, "fulfill its financial obligations" to WHO - adding it would work with the other 193 member states on reforms.
Biden's predecessor, Donald Trump, halted funding to the WHO - announcing plans to withdraw in July 2021.
He accused the WHO of being "China-centric" in the initial stages of the outbreak, a charge rejected by Tedros.