A fast-spreading variant of Sars-CoV-2 – the virus that causes Covid-19 – compelled Boris Johnson to scale back his government’s “Christmas bubble” plans for England, including a “stay at home” order covering London and much of the south and east of England.
These additional restrictions on millions of people may have to remain in place for several months until vaccines have been rolled out across the UK. But what can scientists tell us so far about this variant, and should we be worried?
What do we know about this new variant?
All viruses, and indeed coronaviruses, mutate all the time, so it is not unexpected that this new variant has emerged.
Dr Muge Cevik, a member of the government’s New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), said that more than 4,000 Sars-Cov-2 mutations had been observed so far, of which maybe a handful appeared to be of any significance.
The chief medical officer for England, Chris Whitty, said the new variant discovered in the south-east could be up to 70% more transmissible and could increase the R value by 0.4 or more. Given the data so far, it does not appear to raise the risk of severe illness or the mortality rate.
In a Nervtag summary released on Sunday, experts wrote that they had “moderate confidence” that the variant demonstrated a substantial increase in transmissibility compared with other variants.
They cautioned, however, that the data was preliminary and based on modelling. Cevik said: “Although the results depend on the quality and quantity of data you feed it, this appears to be an important variant based on genetic data – it is potentially its more transmissible but we don’t know how much and we don’t have absolute certainty … Right now, we can’t make a causal relationship, it’s only an association effect.”
The data accumulated so far is consistent with the understanding that the variant is more infectious, or able to spread more efficiently, but we do not have laboratory-based confirmation of that or any idea of why it is spreading faster, said Stuart Neil, a professor of virology at King’s College London.
The variant was associated with 10% to 15% of cases in certain areas a few weeks ago, but last week it jumped to roughly 60% of cases in London, he said,
What do we not know?
Of most concern to scientists at the moment are changes in the variant’s spike protein – the part of the virus that allows it to infiltrate cells in the lungs, throat and nasal cavity by interacting with a receptor called ACE-2, said Neil.
The mutation on the spike protein may enhance the virus’s ability to interact with ACE-2, giving it a growth advantage, he said. On the other hand, the spike protein is the bit of the virus that the vaccines are designed to develop antibodies against, so this mutation could impede the vaccine from doing its job. “It’s something that really does need to be monitored,” he said.
Another big concern is that it is still unclear how many factors had been driving up the transmission in recent weeks, Cevik said. It is likely the variant has influenced transmissibility, but high rates of transmission have also been observed in of areas under higher restrictions.
“Sometimes it comes back to the uncomfortable fact about social inequalities. Lockdowns have limited effects on people who can’t work from home,” she said.
Should restrictions be tightened if there are so many unknowns?
It is always difficult to make decisions based on limited data, but given what we know about this variant so far, experts say it is important to err on the side of caution.
“We may see trends, but they may not pan out later on. In this current situation I think … it’s probably too early to tell. But,it was a bit difficult not to act on it, especially since there was a plan for families to come together over Christmas,” Cevik said.
Prof Andrew Hayward, a professor of infectious disease epidemiology at University College London and a member of the Scientific Advisory Group for Emergencies (Sage), said: “London and the south-east are very far ahead, but it only took them one or two weeks to really move from relatively low levels to very high levels and so it feels to me as though it’s going to be inevitable that tougher restrictions will be needed across the country.
“As usual, as always really, it’s better to go in harder earlier if you want to avoid the maximum number of deaths.”
He said the tighter restrictions were an effort to reduce transmission until as many vulnerable people as possible could be protected.
“That would buy us many more weeks in which we could get people vaccinated, and would save … in my view, tens of thousands of lives.”
Is social distancing guidance sufficient if the variant is more transmissible?
We do not understand enough about the variant to know its impact on existing guidance in terms of social distancing and mask wearing, experts says.
Catherine Noakes, professor of environmental engineering for buildings at the University of Leeds and a member of Sage, said: “I think a lot of people are quite relaxed now around distancing, and we do have to remember the risk goes up the closer you get to somebody.
“We need to be taking as many steps as we can to reduce our potential exposure to it … where interactions are necessary, that we’re really rigorous in applying the measures that we’ve got.”
Should schools reopen in January given what we know about the variant?
It is a great advantage that schools are not open at this time, said Hayward. “I think one of the questions to me is whether it’s really sensible to be going back early in January even with a staggered start for planning to get all students back to school.
Neil said: “The scientist in me says the most effective way to block virus transmission is to limit any contact between anyone that could pass the virus on. But there’s the other half of me, the parent, who sees just how potentially damaging the effect on limiting children’s development and education through closing the schools can have.
“My feeling is that the last thing you should possibly consider is closing the schools. I would, however, advocate a far more aggressive prospective testing of staff in schools.”
Should we be worried?
“I think we already have enough information to know that this variant has the potential to cause a major further epidemic, worse than we had previously predicted,” Hayward said, noting that an increase in transmissibility, even given the same mortality rate, would lead to many more deaths.
Noakes said: “I think over the next few months we’re going to be balancing restrictions … until we have sufficient coverage with the vaccine to be able to relax a little bit.”