The UK is going to see a “really rather large wave of Omicron” and deaths in the next few months, a scientist advising government has said, as he warned coronavirus would keep evolving to escape immunity.

Asked about the trajectory of the Covid pandemic, Professor John Edmunds, a member of the Scientific Advisory Group for Emergencies (Sage), told a Royal Society of Medicine briefing that “we’re certainly not out of the woods”, adding that sequencing suggested Omicron had been around since mid-October.

He added: “I think over the next two months, we’re going to see a really rather large wave of Omicron, we’re getting large numbers of cases and that will result in a large number of hospitalisations and, unfortunately, it will result in a large number of deaths, I’m pretty sure of that.

“What happens next? It’s pretty clear the virus hasn’t done with evolution. It’s going to continue to evolve.

“I’ve long thought that what we’ll start to see is that the virus evolves towards being more of an immune escape than necessarily more transmissible.”

He said he thought the virus would continue to evolve to evade existing immunity “once we have high levels of immunity in the population, because that’s the selective pressure acting on the virus”.

He added: “I think that’s what we’ve just seen. Omicron is … able to evade much of our wall of immune resistance, not all of it, but it is able to get around some of it.

“And I think that’s probably the way that the virus will continue to move, shifting to get around our defences, mainly through evading the immune response.”

Prof Edmunds said he would be very surprised if updated vaccines to tackle variants were not needed.

Adding to the discussion, Professor Peter Openshaw, a member of the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), said he thought that “over time, as this becomes a virus to which everyone is exposed in childhood and then maybe gets reinfected during  later childhood and the teens and through to adulthood, when they become parents, you know, as it builds in and becomes part of the landscape of viruses which we encounter, I think it’s still going to be a significant cause of serious lower respiratory tract infection and it’ll become one of the viruses that enter the differential diagnosis when somebody comes in with, say, winter flu-like illness”.

Earlier, Prof Edmunds told the webinar he was in favour of restrictions to tackle the current wave.

“Unfortunately, if we wait, because this thing is doubling so quickly, if we wait until we see significant numbers of cases in hospitals and in hospitals here in the UK … it will be far too late to act,” he said.

He added: “I think it’s a necessary evil … it’s very damaging for parts of the economy, the hospitality sector, retail sector in particular – they’re going to be affected.

“Unfortunately, we have to do it. The rate at which this virus is spreading is doubling every two or three days.

“If you think what that means in a week, you go through about three doublings in a week, so the epidemic doubles and doubles again and doubles again … So you know, if you’ve got, let’s say, 1,000 infections today and then in a week’s time, you’ve got 8,000.

“And, you know, and in two weeks’ time you’ve got 64,000.

“So that’s why we have to take measures now. Even though there’s very few cases here now, and it seems like an overreaction, it absolutely is not an overreaction.”

Prof Edmunds said Omicron was a “step back” but urged people to have their booster vaccines, adding that they were “likely to offer some protection, particularly against severe disease”.

He added: “So I think it’s absolutely critical that people get a booster dose as rapidly as possible – that is our best defence, I think it will help very significantly, but I still think that we’re likely to be under quite a lot of pressure in very short time.”

He also said he was in favour of vaccinating young children, adding that in the UK the “Delta wave has been driven really by school-aged children”.

He said “now you see equivalent rates of infection in primary school-aged children as you do in secondary school” and “every child who is infected will expose an adult”.

He added: “They must – they all live at home with adults.

“So every single one will expose an adult to coronavirus, and so from that, transmission can occur particularly if the adult is unvaccinated. But even with vaccines there is not 100% protection.”