From BBC - on boosters, waning immunity and endemic equilibrium:
Prof Paul Hunter from the University of East Anglia says a widespread booster campaign may not be needed as the vaccines are still effective at preventing serious disease in many people.
But he's told the PA news agency the boosters should be given quickly to over-80s and the clinically vulnerable.
“The evidence is that these people won’t have responded that well to vaccine," says Prof Hunter.
“As far as I’m concerned there is no debate whatsoever about that group, they should be boosted and they should be boosted pretty soon."
Although protection for other groups will be waning, he says the vaccines will "hopefully" prevent serious illness for several years.
He also says Covid-19 is approaching the "endemic equilibrium", the number of cases we should expect to see per day forever. In other coronaviruses that have been circulating for many years in humans, this is about 45,000 cases a day, Prof Hunter says.