Coronavirus vaccines must be made available around the world in an effort to keep cases down and prevent new mutations which could escape the effects of the jabs, an expert has warned.
Sir Jeremy Farrar, a member of the British government's Scientific Advisory Group for Emergencies (Sage), said the amount of virus circulating in the world will determine the chances of a new variant emerging.
He said new strains are "a warning of what is coming, which we must take incredibly seriously" and suggested countries with access to vaccines could donate a percentage of their doses through the international Covax drive which aims to ensure equitable access.
While variants detected so far do not appear to get round the vaccines, something Sir Jeremy described as "hugely positive", he warned that we are "in something of a race" with a virus which is bound to mutate over time.
He told BBC Radio 4's Today programme: "In the future I think we will see variants that escape from the vaccines.
"The thing to do at the moment is to vaccinate as many people as we can in the world to drive down the amount of transmission and prevent these new variants coming.
"That's in our national interests, it's in an equitable and ethical interest, and it's in the world's interests to do so."
Asked if so-called vaccine nationalism is now a reality, including in Europe, he said: "Yes, I'm afraid it is and it's something that we absolutely have to negotiate, we have to avoid, and it doesn't serve anybody to have these fights over vaccine supply."
He said the only answer is to "drive down transmission, to keep it low and to make these vaccines available globally, otherwise we will see new variants coming up, new strains of this virus which will come back to all of our countries".
At a Downing Street briefing on Wednesday, both Professor Jonathan Van-Tam, deputy chief medical officer for England, and chief scientific adviser Sir Patrick Vallance said that, while there is no clear data yet on the extent to which vaccines will reduce transmission, the scientific thinking is that there will likely be "some effect".
Sir Jeremy said that, while travel restrictions "buy you time", they will not prevent new variants arriving eventually, adding that he does not think the current rules on travel should stay in place for the rest of the year.
He said: "The way to avoid that, which would be very damaging for all of us, economics and finance as well, the way to avoid that is to get vaccines to the world, reduce the amount of transmission around the world, reduce the chance of new variants, and protect the world."
Asked about the March 8 date for the earliest reopening of schools in England, the director of the Wellcome Trust said he is "not in favour of setting deadlines today for when you may open them", adding that it all depends on where transmission is at the time.
Sir Jeremy said it will take "a very long time" for cases to come down and pressures on the NHS to ease, and that lockdown restrictions must be lifted "in a very smart, considered and very cautious way, otherwise we're back to square one".
In a statement, he said a percentage of vaccine doses could be given away without affecting the national rollout.
"We are not passive observers, we have a choice," he said.
"With limited global supply of vaccines in 2021, distributing all doses as strategically as possible is a scientific and economic imperative.
"Countries with existing deals could donate a percentage of doses without taking away from the national effort to protect the most vulnerable in society and healthcare workers.
"All such doses should be donated through Covax.
"We also strongly encourage countries making future deals to share doses through Covax.
"The most vulnerable everywhere, including healthcare workers, must be protected first."