US President Donald Trump and UK Prime Minister Boris Johnson discussed the global response to coronavirus during a phone on Friday.
Downing Street said the two men spoke about the “ongoing international co-operation to develop a vaccine”, the BBC reported.
Trials have begun on vaccines across the world, including in the US and UK.
A Number 10 spokesman said they also discussed the next G7 summit scheduled to be held in Washington next month and stressed the “importance of leaders meeting in the US in person if possible” .
Earlier this week, a White House spokeswoman said the US planned to hold the summit as planned “towards the end of June”.
The White House added that the two men also discussed “progress on reopening” their respective countries amid continued lockdowns.