The head of the Oxford Vaccine Group has said the UK may not need a booster shot campaign because protection remains strong among those who are vaccinated.
Prof Sir Andrew Pollard said there was no current evidence that third shots should be distributed because scientists have yet to see a “significant breakthrough” in Covid cases among the fully vaccinated.
He said he would prefer to see vaccine doses donated to poorer countries where immunisation rates remain dangerously low.
"We have this astonishing moment we’ve arrived at where we’ve now distributed globally more than three billion doses of vaccines", he told BBC's Radio 4 Today programme on Monday.
"If we go back to the projections from a year ago, that would be enough doses to vaccinate everyone in the world who was at high risk of dying from Covid ... and yet here we are where 55,000 people died last week. If you’re in a poorer country, you’re very unlikely to be vaccinated if you’re in one of those groups - less than 1 per cent of the doses have gone to poor countries so far."
Britain's Joint Committee on Vaccination and Immunisation (JVCI) has advised that a booster shot campaign may need to begin in the UK within months to guard against a surge of cases in winter, when hospitals are normally under significant strain.
It has recommended vulnerable people should be injected with third doses first before progressing through the age groups from oldest to youngest.
Prof Pollard, who is also the chairman of the JVCI, said "we haven’t got evidence so far that we do need boosters" but he cautioned the situation may change.
He said it was scientifically possible that the body's immune system may "remember" to fight Covid-19 even if antibody levels wane.
"The reason for that is our immune system is amazing - it remembers the vaccine doses we’ve had for the rest of our lives, so it can kick in and spring into action when we meet the virus again to provide protection", he said.
"At the moment, we don’t know whether that memory is going to be enough to protect us forever or whether it will need topping up. At this moment, we don’t see evidence of that decline in antibodies that is seen to the extent where we’re not going to be protected."