Vaccine-conferred immunity declines but the booster regime – under which more than 14 million people have received a third dose – means there will not be a large population of unprotected vulnerable people.

A rapid increase in transmission rates would only come about with significant changes in behaviour and, with many people now back to pre-pandemic routines, that seems unlikely. The likelihood of both transpiring at the same time is extremely slim.

According to Sage, another variant could upset the equation – but surveillance from the UK Health Security Agency has yet to identify a more potent form than the delta variant. The recent AY.4.2 sub-variant is thought to be only marginally more transmissible and no more potent.

However, the NHS remains in a difficult position as it tries to clear a record-breaking backlog of patients awaiting treatment for other conditions.

Prof John Edmunds, a member of Sage, told BBC Radio 4’s The World at One: “I think it’s really important that we boost immunity in older individuals and then we might be able to avoid any significant fourth wave.

“We’re going to have high levels of infection for many months, so I think the NHS will unfortunately be under significant strain – it may not get to breaking point, where we were close to before – but significant strain for a very long period of time is certainly on the cards.”