Covid is unlikely to mutate into a much deadlier variant because there “aren’t many places for the virus to go”, the lead scientist behind the Oxford vaccine has said.
Dame Sarah Gilbert said that viruses tended to become less virulent over time as they spread through a population which was becoming more immune.
Speaking on a Royal Society of Medicine webinar about variants on Wednesday, Dame Sarah said: “The virus can’t completely mutate because its spike protein has to interact with the ACE2 receptor on the surface of the human cell, in order to get inside that cell.
“If it changes its spike protein so much that it can’t interact with that receptor, then it’s not going to be able to get inside the cell. So there aren’t very many places for the virus to go to have something that will evade immunity but still be a really infectious virus.”
She added: “We normally see that viruses become less virulent as they circulate more easily and there is no reason to think we will have a more virulent version of Sars-CoV-2.
“We tend to see slow genetic drift of the virus and there will be gradual immunity developing in the population as there is to all the other seasonal coronaviruses. There are four of them and they’ve been circulating for decades and we’re not even aware of them.
“So we already live with four different human coronaviruses that we don’t really ever think about very much and eventually Sars-CoV-2 will become one of those. The question of how long it’s going to take to get there and what measures we’re going to have to take to manage it in the meantime.”
Keeping an eye on beta and lambda variants
Experts are still concerned about the beta and lambda variants, but neither has managed to get a strong foothold in Britain.
Professor Sharon Peacock, the executive director of the Covid-19 UK Genomics Consortium, which monitors variants for the Government, also told the webinar: “It’s watch and wait, but delta is top of the list and other variants are not particularly concerning at the moment.
“It has been pretty quiet since delta emerged and it would be nice to think there won’t be any new variants of concern. If I was pushed to predict, I think there will be new variants emerging over time and I think there is still quite a lot of road to travel down with this virus.”
Prof Peacock said that it was important to genetically sequence people who became ill after travelling to check that new variants were not being imported into Britain as they were the “canary in the coal mine”.
However, she said that vaccinating as many people as possible around the world was the best way to prevent the emergence of worrying mutations.
“If we don’t vaccinate people and there is uncontrolled transmission and infection, then that is the right training ground for the virus to really emerge. That is a real variant of concern,” she added.
“If we don’t have very much infection, then the virus doesn’t have much chance to mutate. So vaccination of the world is not only the morally right thing to do, but the strategically right thing to do if we are going to protect the world. Sequencing travellers are the canary in the coal mine as they will be where new variants are emerging.”
Prof Peacock also said she had not completely ruled out that the virus had been engineered or had leaked from a lab.
“There is reason to think the virus did emerge from an animal host,” she said. “I haven’t seen any definitive evidence it is an engineered virus or escaped. But what this virus has taught me is to be humble when I’m wrong, and I’ve been wrong quite a few times and have had to become nimble in changing my mind.
“So if further evidence comes along that shows the virus as being engineered, I would be willing to consider that. But at the moment, in my view it has arisen from an animal.”