Streets in Glasgow city center were abandoned on January 5 after the UK imposed a strict lockout to curb the spread of a new SARS-CoV-2 variant.
ANDY BUCHANAN / AFP via Getty Images
By Kai Kupferschmidt
Science‘COVID-19 reporting is supported by the Pulitzer Center and the Heising-Simons Foundation.
For COVID-19 researchers, the new year brings a strong sense of déjà vu. As in early 2020, the world is anxiously watching a virus that is spreading in one country and trying to analyze the risk for everyone else. This time, it’s not a completely new threat, but a rapidly spreading variant of SARS-CoV-2. In the south-east of England, where the B.1.1.7 variant first caught the attention of scientists last month, it has quickly replaced other variants and is possibly the forerunner of a new, particularly dangerous phase of the pandemic.
“One concern is that B.1.1.7 will now become the dominant global variant with its higher transmission and that it will still drive a very, very bad wave,” says Jeremy Farrar, an expert in infectious diseases. Of the Wellcome Trust. While the pandemic’s trajectory in 2020 was fairly predictable, ‘I think we are now going into an unpredictable phase,’ as a result, Farrar says.
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The concern has led some countries to speed up vaccine authorization or discuss dosing systems that could protect more people quickly. But because the new variant appears in several countries, many scientists are asking governments to strengthen existing controls as well. British Prime Minister Boris Johnson on January 4 announced difficult new restrictions, including closing schools and urging people not to leave their homes unless strictly necessary. But other countries hesitated. “I feel that we are currently in a different situation where a lot of Europe is sitting and watching,” says virologist Emma Hodcroft of the University of Basel. “I really hope we can realize this time it’s our early alarm bell, and this is our chance to avoid this variant.”
In announcing the UK restrictions, Johnson said the new variant is between 50% and 70% more transferable. But researchers were careful to point out uncertainties. Cases have increased in the UK over the past month, but the increase has occurred as different parts of the country have different levels of restrictions and amid changes in people’s behavior and regional infection rates in the run – up to Christmas – a complex scenario ” it makes it difficult to indicate the effect of the new variant, ‘says evolutionary biologist Oliver Pybus of Oxford University.
However, evidence increased rapidly that the many mutations of B.1.1.7, including eight in the major protein, improved proliferation. “We rely on multiple streams of imperfect evidence, but virtually all of the evidence now points in the same direction,” says Adam Kucharski, a modeling student at the London School of Hygiene & Tropical Medicine. An analysis by Public Health England, for example, showed that approximately 15% of the contacts of people infected with B.1.1.7 in England tested positive themselves, compared to 10% of the contacts with other variants.
If other countries that detect B.1.1.7 also see it rise, it will be ‘the strongest evidence we will have’, says Pybus. In Ireland, where infections have also risen rapidly, the variant now accounts for a quarter of consecutive cases. And data from Denmark, which leads the European Union in the order of SARS-CoV-2, is also not reassuring. Routine monitoring there has included the variant dozens of times; its frequency went from 0.2% of consecutive genomes in early December to 2.3% 3 weeks later. “We have had an example of a poster child of exponential growth in Denmark for the past 4 weeks,” says genomicist Mads Albertsen of the University of Aalborg. The numbers are still too low to draw strong conclusions, Albertsen warns, but if the trend continues, it will be a clear sign that many countries may face the same problems as the UK. “We have to prepare for it to happen elsewhere,” Hodcroft said.
I really hope we can realize this time that it’s our early alarm clock, and this is our chance to avoid this variant.
The lack of evidence – so far – that the new variant makes people sicker is little consolation. Increased transmission of a virus is far more insidious than increased pathogenicity, because its effects grow exponentially, Kucharski says. “If you have something that kills 1% of people but a large number of people get it, it will result in more deaths than something that gets a small number of people but kills 2% of them.”
If the UK estimates that a 50% to 75% increase in the reproduction number of the virus, or R, is true, “the spread of the virus has become much more difficult”, says Viola Priesemann, a physicist of the Max Planck Institute for Dynamics and Self-Organization which models the pandemic and the consequences of non-pharmaceutical interventions, such as physical distance and school closure. “In Germany, you need two major additional measures to keep the reproduction number below 1,” says Priesemann.
Isolating patients and locating, quarantining and testing their contacts is one part of every effort to do so; these measures alone can reduce R from about 2 to about 1, Priesemann showed for Germany. But the effect breaks down when case numbers reach a critical threshold and public health authorities are overwhelmed, meaning that stricter measures could later help spread the new variant. “This is another reason to go for very low numbers,” said Priesemann, who co-authored a December 2020 letter to the The Lancet calls on Europe to adopt a joint strategy to bring down infections rapidly. Hodcroft agrees. “The case has never been stronger,” she says. ‘What’s the worst case scenario here? We overspend and we get things so low that we can get rid of a lot of constraints. ”
The attenuation of infections has the added benefit of reducing the chances of the virus developing further. Other variants have already emerged, especially one called 501Y.V2 in South Africa, which is just as worrying as B.1.1.7, Farrar adds. “It’s essentially a numbers game: the more virus circulates, the greater the chance that mutants will appear,” he says. In the long run, mutations can arise that threaten the effectiveness of vaccines.
It is disturbing to feel that the world is back to where it was in early 2020, says epidemiologist William Hanage of the Harvard TH Chan School of Public Health. ‘But we have to stop this virus. … Fatalism is not a non-pharmaceutical intervention. ‘