The virtual WHO Facilitation Council aims to help fill a $27 billion funding gap for the WHO-backed programme, called the Access to COVID-19 Tools (ACT) Accelerator, that is aimed at broadening global access to COVID-19 fighting tools.
The United States had previously been an observer to ACT.
Washington, the top donor to the WHO, has already pledged $4 billion for the global pandemic response. WHO's Special Envoy for the ACT Accelerator, Andrew Witty, a former GlaxoSmithKline CEO, said talks on further US contributions were ongoing.
A meeting document gave preliminary total estimates for how much major economies would be expected to give, showing between $6-$9 billion for the United States and about $2-$4 billion for Japan and Germany.
"There was general support for the burden-sharing framework," Dag Inge Ulstein, Norway's minister of international development who co-chaired the meeting, told Reuters.
"We got a really good response from the actors and the US coming back has created momentum."
Tedros, at the same meeting, expressed fresh concerns about vaccine inequity, noting that 90 per cent of countries rolling out COVID-19 vaccines were wealthy and that 75 per cent of doses had been deployed to just 10 countries.
South African health minister Zweli Mkhize, the other co-chair, called these "alarming and disappointing numbers which we need to change".