Dr Mike Tildesley, a member of the Scientific Pandemic Influenza Modelling group, said: “I would hope that with a very successful vaccination campaign, the idea of a winter lockdown is a long way away.
“But it is certainly true that if we don’t get good immunity across the population there may need to be perhaps further measures taken.
“So it’s really important that we encourage people to come forward when eligible to take those booster jabs.”
Dr Tildesley said there was evidence that immunity was waning among over 50s and vulnerable adults.
He said it was vital that protection is as high as possible ahead of the colder winter months.
Asked whether we may need booster jabs every year, he said: “I think it’s possible.”
Professor Peter Openshaw, chairman of the New and Emerging Respiratory Virus Threats Advisory Group, warned Covid “isn’t done”.
He said: “If we look at the people who are sadly still dying of Covid, it’s predominantly in those over 50.
“And it’s that group that really does need to have the boosters – particularly those over 60 and especially in those over 70.”