Ministers have been warned lockdown restrictions have to be relaxed “very slowly, very cautiously” after scientists said vaccines must prove to be highly effective at preventing transmission to avoid a future spike in deaths.
Public Health England’s coronavirus strategy chief Dr Susan Hopkins said on Sunday measures must be eased slowly so “we can clamp down quite fast” if an increase of cases is seen.
Her comments came as preliminary research from scientists advising the Government suggested a “huge surge in deaths” will only be avoided as restrictions are eased if vaccines have a high uptake and are highly effective at blocking infection and, therefore, transmission.
Academics on the Scientific Pandemic Influenza Group on Modelling (Spi-M) said deaths are only “substantially reduced” under a gradual relaxation scenario if vaccines are able to prevent 85% of infections in vaccinated individuals, rather than just reduce the severity of disease.
Dr Hopkins told the BBC’s Andrew Marr Show: “We have learnt, as we did on the first occasion, we have to relax things really quite slowly, so that if cases start to increase we can clamp down quite fast.
“Any releases that we have will have to happen very slowly, very cautiously, watching and waiting as we go, with a two-week period to watch and see the impact of that relaxation because it takes that to see what’s happening in the population.”
Cabinet minister Liz Truss was asked if social distancing measures may need to last for the rest of the year in response to the research commissioned by Spi-M and worked on by four members of the advisory group.
“I don’t want to make predictions about the situation in the autumn, I think it’s far too far away,” Ms Truss told Sky’s Sophy Ridge on Sunday.
The group, from the Warwick University, modelled various scenarios of easing restrictions, known as non-pharmaceutical interventions, or NPIs, alongside how effective existing vaccines prove to be.
“Only vaccines that offer high infection-blocking efficacy with high uptake in the general population allow relaxation of NPIs without a huge surge in deaths,” they said in a paper published last week ahead of being peer reviewed.
Their model suggested a gradual relaxation of restrictions beginning in April and ending in the winter only prevents a severe peak if vaccines have 85% infection efficacy.
The research also studied the effects of vaccines having 35% and 60% infection efficacy, and each produced surges when of more than 1,500 deaths per day when restrictions waned.
They accept it is a pessimistic view as behaviour and Government policy would likely to change if relaxations caused the number of hospital admissions to rise again, while they did not examine vaccines having efficacies between those three groups.
The Moderna jab is said to have 94.1% efficacy against Covid-19. Data from Pfizer and BioNTech indicates the vaccine is 95% effective against the disease.
But this is different from the infection efficacy in the study, which considers the prevention of infection and therefore the ability to transmit the virus onwards.
England’s deputy chief medical officer Jonathan Van-Tam has said vaccines’ impact on transmission is not yet understood, with Public Health England working to ascertain vaccines’ effect on infection.
He argued the jabs with high levels of effectiveness in trials “really couldn’t fail to have some effect on transmission”.
“And the question is really less ‘will they’ but ‘to what extent’?” he told a Downing Street press conference.
England’s chief medical officer Professor Chris Whitty has previously warned some restrictions may have to return next winter.
“We might have to bring in a few in the next winter for example, that’s possible, because winter will benefit the virus,” he said.
The Government will next month publish its plan for easing England’s third national, with March 8 earmarked for the first relaxation, with the wider reopening of schools.
Dr Sam Moore, the epidemiological modeller at Warwick who led the team in the Spi-M commissioned research, warned that even if vaccines do have a significant impact on reducing infections, the impact will not be seen “for some time to come”.
“So I think they have to relax slowly and we’re going to have to be patient. And we need a very high uptake in order to have this effect,” he said.
In a record daily rise, official data showed a 598,389 rise in the number of people vaccinated, bringing the UK-wide total to 8,977,329.
But it came as a further 587 people died within 28 days of testing positive for Covid-19 as of Sunday, bringing the official death toll to 106,158.