Select Page


Viral mutations may cause another ‘very, very bad’ COVID-19 wave, scientists warn – Science Magazine

Jan 5, 2021 | Uncategorized | 0 comments



Streets in downtown Glasgow were deserted on 5 January after the United Kingdom imposed a strict lockdown to curtail the spread of a new SARS-CoV-2 variant.

ANDY BUCHANAN/AFP via Getty Images

Sciences 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 spread in one country and trying to parse the risk for everyone else. This time it is not a completely new threat, but a rapidly spreading variant of SARS-CoV-2. In southeastern England, where the B.1.1.7 variant first caught scientists’ attention last month, it has quickly replaced other variants, and it may be the harbinger of a new, particularly perilous phase of the pandemic.

“One concern is that B.1.1.7 will now become the dominant global variant with its higher transmission and it will drive another very, very bad wave,” says Jeremy Farrar, an infectious disease expert who heads the Wellcome Trust. Whereas the pandemic’s trajectory in 2020 was fairly predictable, “I think we’re going into an unpredictable phase now,” as a result the virus’ evolution, Farrar says.

The concern has led some countries to speed up vaccine authorizations or discuss dosing regimens that may protect more people rapidly. But as the new variant surfaces in multiple countries, many scientists are calling for governments to strengthen existing control measures as well. U.K. Prime Minister Boris Johnson announced tough new restrictions on 4 January, including closing schools and asking people not to leave their homes unless strictly necessary. But other countries have hesitated. “I do feel like we are in another situation right now where a lot of Europe is kind of sitting and looking,” says virologist Emma Hodcroft of the University of Basel. “I really hope that this time we can recognize that this is our early alarm bell, and this is our chance to get ahead of this variant.”

In announcing the U.K. restrictions, Johnson said the new variant is between 50% and 70% more transmissible. But researchers have been careful to point out uncertainties. Cases have soared in the United Kingdom over the past month, but the rise occurred while different parts of the country had different levels of restrictions and amid changes in people’s behavior and regional infection rates in the run-up to Christmas—“a complex scenario” that makes it hard to pinpoint the effect of the new variant, says evolutionary biologist Oliver Pybus of the University of Oxford.

Yet evidence has rapidly increased that B.1.1.7’s many mutations, including eight in the crucial spike protein, do enhance spread. “We’re relying on multiple streams of imperfect evidence, but pretty much all that evidence is pointing in the same direction now,” says Adam Kucharski, a modeler at the London School of Hygiene & Tropical Medicine. For instance, an analysis by Public Health England showed about 15% of the contacts of people infected with B.1.1.7 in England went on to test positive themselves, compared with 10% of contacts of those infected with other variants.

If other countries that have detected B.1.1.7 also see it surge, it will be “the strongest evidence we will have,” Pybus says. In Ireland, where infections have risen rapidly as well, the variant now accounts for a quarter of sequenced cases. And data from Denmark, which leads the European Union in the sequencing of SARS-CoV-2, aren’t reassuring either. Routine surveillance there has picked up the variant dozens of times; its frequency went from 0.2% of sequenced genomes in early December to 2.3% 3 weeks later. “We have had what looks like a poster child example of exponential growth these last 4 weeks in Denmark,” says genomicist Mads Albertsen of Aalborg University. The numbers are still too low to draw strong conclusions, Albertsen cautions, but if the trend continues it will be a clear sign that many countries may face the same problems as the United Kingdom. “We should start preparing ourselves for the fact that this is happening elsewhere,” Hodcroft says. 

I really hope that this time we can recognize that this is our early alarm bell, and this is our chance to get ahead of this variant.

Emma Hodcroft, University of Basel

The lack of evidence—so far—that the new variant makes people sicker is little consolation. Increased transmissibility of a virus is much more treacherous than increased pathogenicity because its effects grow exponentially, Kucharski says. “If you have something that kills 1% of people but a huge number of people get it, that’s going to result in more deaths than something that a small number of people get but it kills 2% of them.”

If the U.K. estimates of a 50% to 75% increase in the virus’ reproduction number, or R, hold true, “keeping the virus from spreading has become a lot harder,” says Viola Priesemann, a physicist at the Max Planck Institute for Dynamics and Self-Organization who has been modeling the pandemic and the effects of nonpharmaceutical interventions, such as physical distancing and school closures. “In Germany, you would need two big additional measures to keep the reproduction number below 1,” Priesemann says.

There’s growing evidence that mutations in a new SARS-CoV-2 variant helped infections in the United Kingdom soar over the past month.

Johns Hopkins University CSSE COVID-19 Data

Isolating patients and tracing, quarantining, and testing their contacts is one part of any attempt at doing so; those measures alone can reduce R from about 2 to about 1, Priesemann has shown for Germany. But that effect breaks down when case numbers reach a critical threshold and public health authorities are overwhelmed, which means tougher measures now can help contain the spread of the new variant later. “It’s yet another reason to go for very low numbers,” says Priesemann, who co-authored a December 2020 letter to the The Lancet calling for Europe to adopt a joint strategy to bring down infections fast. Hodcroft agrees. “The case has never been stronger,” she says. “What’s the worst-case scenario here? We overshoot and we get cases so low that we can get rid of a lot of restrictions.”

Curtailing infections sharply has the added benefit of reducing the chances for the virus to evolve even further. Already other variants have emerged, notably one called 501Y.V2 in South Africa, that are just as worrying as B.1.1.7, Farrar adds. “It is essentially a numbers game: The more virus is circulating, the more chance mutants have to appear,” he says. In the long term, mutations could arise that threaten the efficacy of vaccines.

It’s dispiriting to feel like the world is back where it was in early 2020, says epidemiologist William Hanage of the Harvard T.H. Chan School of Public Health. “But we have to stop this virus. … Fatalism is not a nonpharmaceutical intervention.”