It is "unlikely" that a coronavirus vaccine will be able to completely stop the spread of infection, the government's chief scientific advisor has warned, adding that the disease may well become endemic in the global population – much like influenza.
He insisted that the strategy of attempting to eradicate the disease, which has been adopted in countries such as New Zealand and Australia, was “not right because it’ll come back”.
The chief scientific adviser pointed to the example of smallpox as the only human disease that has been “truly eradicated” from the population thanks to a “highly effective” vaccine.
Due to the likelihood that a coronavirus vaccine would not be able to fully block transmission, it’s probable that the disease will be allowed to keep on circulating and become endemic, Prof Vallance said.
“Now of course we can’t be certain, but I think it's unlikely we'll end up with a truly sterilising vaccine – i.e. something that completely stops infection,” he told the select committee. “It's likely that this diseases will circulate and be endemic.
“I think that's the view of many people on Sage that that's a likely outcome. Clearly, as management becomes better, as you get vaccination which would decrease the chance of infection and severity of disease – or whatever the profiles of the vaccines are – this then starts to look more like annual flu than anything else. That may be the direction we go in.”
It is expected that some of the vaccines currently in development may prove more effective in reducing the severity of disease for people who are infected, while other candidates may be more successful in blocking transmission among younger age groups.
Addressing the policy of ‘Zero-Covid’, Prof Vallance said: “The notion of eliminating Covid from anywhere is not right because it'll come back.
“It's worth reflecting that there's only one human diseases that's been truly eradicated and that's with a highly effective vaccine – smallpox. So it's a very difficult thing to do.”
He explained that the government would need to increase its testing in order to identify asymptomatic patients and thereby stand any chance of eradicating the virus from the population.
According to current estimates, Prof Vallance said, infected patients who do not display any symptoms of Covid-19 constitute roughly 60 per cent of all cases, making it difficult for authorities to get a grasp of the epidemic in the UK.
“Would I like to test far more? Do I think the UK would be in a better position if it could test more? Yes, because we know the only way you pick up a lot of people is through testing,” Prof Vallance said.
“And the testing then needs to be linked to the action of isolation. It's no good to just test, you need to do something in terms of isolation. The more you can get out there and test across asymptomatics, particularly in areas like care homes and hospital settings ... the better.”
Although he said the UK was testing more than any other country in Europe, he said current levels were “nowhere near enough” to realise the goal of ‘zero-Covid’.
New Zealand has twice appeared to have eliminated the virus – first during the summer, before an outbreak in Auckland sent the country back into lockdown, and more recently this month, when a three-week streak without a local case ended after a port worked tested positive.
Although the situation has since been contained, it nonetheless served as a “reminder that Covid-19 is not going away any time soon”, as Dr Ashley Bloomfield, the country’s director general of health, put it.
Sir Patrick also told the parliamentary select committee that a flu pandemic continues to remain the greatest threat to the biosecurity of the UK.
He warned that other infectious diseases which pass from animals to humans, like coronavirus, and antimicrobial resistance also pose major health risks.
“Pandemic flu remains the highest risk because the flu virus mutates so readily and can make the species jump,” he said. “We just know from history that's a big risk.
“We've now seen the coronavirus can make that leap in quite a dramatic way as well, so you have to say that a coronavirus outbreak with a mutation is possible, although this virus mutates far less easily and much less quickly than flu.”
He added: “I think other jumps from animals to humans and other infectious diseases could come.”