Renewing its call on Friday (June 26) for global collaboration against the pandemic, it said $3.4 billion had been contributed for the coalition to date, leaving a funding gap of $27.9 billion.
Of that, $13.7 billion was required "to cover urgent needs", Ngozi Okonjo-Iweala, the Director General Special Envoy for the ACT-accelerator, said.
The WHO is working with a large coalition of drug-development, funding and distribution organizations under what it calls the ACT-Accelerator Hub.
It aims to scale up delivery of 2 billion vaccines doses, including 1 billion to be bought by high- and middle-income countries, by the end of 2021.
Astrazeneca's COVID-19 vaccine is probably the world's leading candidate and most advanced in terms of development, the WHO's chief scientist said on Friday.
Soumya Swaminathan said that Moderna's COVID-19 vaccine candidate was also "not far behind" Astrazeneca's, among more than 200 candidates, 15 of which have entered clinical trials.
Swaminathan, speaking to a news briefing, called for considering collaborating on COVID-19 vaccine trials, similar to the WHO's ongoing Solidarity trial for drugs.