The letter was sent to the prime minister at a time when a government scientific advisor warned that Britain could face another coronavirus wave as big as the current one if lockdown restrictions were all lifted.

Professor Steven Riley, a member of the Scientific Pandemic Influenza Group on Modelling, has said the rollout of the vaccination program did not mean coronavirus controls could be dropped.

"No vaccine is perfect," he told a BBC radio program. "We are certainly going to be in the situation where we can allow more infection in the community but there is a limit."

"If for some reason we were to choose to just pretend it (coronavirus) wasn't here any more then there is the potential to go back to a wave that is a similar size to the one that we are in now," he added.

The prime minister confirmed Saturday that the reopening of schools "is still his priority", followed by opening shops and then hospitality.

This was further reiterated by British Foreign Secretary Dominic Raab, who said on Sunday that the British government remained focused on reopening of schools on March 8.

The British ministers said they are confident they will meet their target of getting an offer of a vaccine to all 15 million people in Britain in their four priority groups, including all over 70s, by Feb 15's deadline.