World leaders sign up to a fundraising drive, which aims to raise $8.3bn over the next month.
European leaders have pledged support for a plan to raise €7.5bn (£6.6bn; $8.3bn) to find a coronavirus vaccine in a jointly signed open letter.
The Brussels-led initiative was set out by European Commission President Ursula von der Leyen on Friday.
The promises come ahead of an online pledging conference on Monday.
UK Prime Minister Boris Johnson will urge countries to "pull together" to meet "the most urgent shared endeavour of our lifetimes".
Mr Johnson, who spent three nights in intensive care with Covid-19, will also confirm the UK's pledge of £388m for vaccine research, testing and treatment.
The conference will be co-hosted by the UK, Canada, France, Germany, Italy, Japan, Norway, Saudi Arabia and the European Commission.
The UN says a return to normal life will only be possible with a vaccine.
Italian Prime Minister Giuseppe Conte, French President Emmanuel Macron and German Chancellor Angela Merkel are also among those who have signed up to the initiative.
In the open letter published in weekend newspapers, the leaders said that the funds raised would "kickstart an unprecedented global co-operation between scientists and regulators, industry and governments, international organisations, foundations and healthcare professionals".
"If we can develop a vaccine that is produced by the world, for the whole world, this will be a unique global public good of the 21st Century," they added.
At the same time, the signatories gave their backing to the World Health Organization in the face of US criticism of its handling of the outbreak.
Dozens of research projects trying to find a vaccine are currently under way across the world. BBC