Lockdown can only be lifted ‘IF Covid vaccine stops transmission – and we still don’t know’, warn Sage
SCIENTISTS have no clue whether lockdown will be lifted in 2021, despite the vaccine roll-out, Sage documents show.
A paper published today suggests that easing restrictions too early could lead to another wave of Covid, and cause tens of thousands more deaths.
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Whether the UK can exit lockdown is “highly dependent” on two things; how many people accept their offer of a jab, and whether the vaccine can actually reduce the spread of the virus.
The vaccines, from Pfizer and Oxford/AstraZeneca, have been shown in clinical trials to help stop someone from getting severe disease, or dying.
They have not yet been shown to prevent someone from silently carrying the virus, although early indications suggest that they do.
It could be at least several months before the crucial question is answered.
The Scientific Pandemic Influenza Group on Modelling, Operational sub-group’s (SPI-M-O) paper, which feeds into the government’s scientific advisory group Sage, dashes hopes the UK can start to move out of lockdown in the spring.
It is planned for the most vulnerable 14 million people to be jabbed by mid-February, after which it was suggested some restrictions could be lifted by Easter, and Brits could “enjoy summer”.
But the modelling shows that lifting restrictions at the end of March – when 20 million people are expected to be vaccinated – could be a huge mistake.
In a worst-case scenario, it could cause deaths to soar to 700 a day by August.
It drops to almost zero if the vaccine can prevent spread of the virus, therefore wiping it out.
Even if a large proportion – 75 per cent – of the over 75s take their vaccine, 40,700 in that age group could still die if lockdown is eased early.
That’s because 25 per cent who have refused their jab would still be vulnerable to catching the disease.
The risk of easing lockdown early
SPI-M-O said there is uncertainty about 2021, writing: “Once the vaccine has been rolled out to the most vulnerable people, there will be scope for partial relaxation of non-pharmaceutical interventions [face masks, hand washing and social distancing].
“But the extent of this scope is highly dependent upon the impact of vaccines on viral transmission.
“Scientists are unlikely to know what effect vaccines have on transmission for at least a couple of months after vaccine rollout.
“If decisions were made to slightly loosen restrictions in the earliest months of rollout, this would happen with no one able to say whether or not to expect a resurgence in cases.”
The group modelled scenarios in which the vaccine reduces transmission by zero per cent, 25 per cent, 50 per cent and 75 per cent.
They consider how many deaths and hospitalisations there would be if the country returned to some level of normality – similar to restrictions in September such as the “rule of six”.
And they applied this to different stages of the vaccine rollout, due to end some time in autumn,
The researchers consider that the virus would still be circulating in any given scenario with an R rate slightly below 1.
Graphs show that if there were partial restrictions eased after 19.5 million people were jabbed, and the vaccine had no effect on cutting transmission, deaths could reach 700 per day and hospitalisations 1,000.
If restrictions were partially loosened when 28 million were jabbed – around half the adult population – deaths could still reach 400 per day around September, and 1,000 hospitalistions.
Under both scenarios, if the vaccines were able to stop transmission at all, deaths would be significantly lower, less than 100 per day.
Can the vaccines prevent Covid transmission?
The vaccines being rolled out in the UK are made by Pfizer/BioNtech and AstraZeneca (Oxford University).
Trials of the Pfizer/BioNTech jab showed it was 95 per cent effective at stopping people becoming ill with Covid-19 if they get infected, after two doses are given, but could not show if it stopped people picking up and passing on the virus.
Officials in Israel released data last week that showed Pfizer’s jab cuts infection rates in half two weeks after the first of the twin doses is given.
The country has inoculated more people per capita than anywhere else in the world.
An Israeli scientist said it was unlikely people who had both shots of the vaccine would carry the virus.
Professor Gili Regev-Yohai, director of Sheba’s Infectious Disease Epidemiology Unit, released early findings of research from Sheba Medical Center in Tel Hashomer on Monday, according to the Jerusalem Post.
She said if vaccinated people catch Covid, they would have a lower viral load, meaning they shed fewer viral particles from their mouth and nose.
This in theory would make them less infectious. But the data has not been published.
The Oxford scientists who developed the AstraZeneca vaccine said their jab showed signs that it reduced spread of the virus.
The team tested people for Covid regularly to assess if people were carrying the virus, even if they showed no symptoms, findings few cases of asymptomatic Covid.
Prof Andrew Pollard, chief investigator of the Oxford trial, said in November: “If that is right, we might be able to halt the virus in its tracks and stop transmitting between people.”
Officials in the UK have said it won’t become clear for a few weeks whether the vaccine programme in the UK is helping to squash the outbreak.
Professor Stephen Powis, national medical director for the NHS in England, said: “It will stop you getting severe illness but we don’t yet know how good the vaccines are at stopping the transmission of the virus – that is data that will become apparent as more people get vaccinated.
“So my advice, get the vaccine if you are offered it, but continue to stick to those social distancing guidelines, that’s the way we will prevent lives being lost and it’s the way we will take pressure off our hospitals.”
The paper said: “If the vaccine significantly reduces transmission, then once a large number of people have been immunised there would be scope for partial relaxation without another epidemic wave.”
SPI-M-O explained in both situations there would be “too many susceptible people” to prevent another wave.
In their modelling, the researchers acknowledge that there will be some people who will not take the vaccine.
And the vaccines being rolled out are not 100 per cent effective – no vaccine used to protect humans against disease is.
There are 5.7 million people over the age of 75.
If three quarters were immunised with a vaccine, a calculated 1.85m of them would not be protected against catching the virus, and potentially getting severe disease.
Even with “careful re-opening” of society, this could lead to 40,700 more deaths in the over 75s. It drops to 23,800 if uptake is 90 per cent.
For perspective, flu vaccine uptake is around 75 per cent.
The paper said: “The key insight from early modelling work is that it is critical to get extremely high vaccine coverage in the most vulnerable groups before non-pharmaceutical interventions (NPIs) are eased (or adherence to them drops) if we are to avoid a very high death toll.
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“If restrictions are gradually lifted before vaccines have sufficiently reduced transmission, then we could see a long plateau with a sustained high death toll.”
Government data up to January 21 shows 5,383,103 first doses of vaccines have been given out so far.
An average of 306,880 doses are being given out per day – more than two million a week.
The Government have pledged to vaccinate two million a week in order to hit their ambitious roll-out targets.