A shopping street in Copenhagen, Denmark, during the closing in January. Keeping the B.1.1.7 variant of COVID-19 at a distance may require additional controls, scientists say.
EMIL HELMS / Ritzau Scanpix / AFP via Getty Images
By Kai Kupferschmidt
Science‘COVID-19 reporting is supported by the Heising-Simons Foundation.
At first glance, the curve of COVID-19 infections in Denmark seems reassuring enough. A nationwide exclusion has led to numbers of more than 3,000 daily businesses dropping to just a few hundred by mid-December 2020. But do not be deceived. “Of course, the numbers look good,” said Camilla Holten Møller of the Statens Serum Institute, which heads a group of experts modeling the epidemic. “But when we look at our models, it’s the calm before the storm.”
This is because the graph really reflects two epidemics: one, which is shrinking rapidly, is caused by older variants of SARS-CoV-2, and a smaller, slow-growing outbreak of B.1.1.7, the variant first introduced in England was recognized and now a big third wave of the pandemic there. If B.1.1.7 continues to spread at the same rate in Denmark, it will become the dominant variant later this month and increase the overall number of cases again, despite the exclusion, says Holten Møller. “It’s a complete game changer.”
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The same thing is likely to happen in many countries without being noticed. But a massive attempt at virus infestation has enabled Denmark, a country of 5.8 million, to track the emergence of the new COVID-19 variant more closely than any other country. “There are currently all eyes on Denmark,” says Kristian Andersen, a researcher on infectious diseases at Scripps Research, which advises the Danish government. “Is there a way in which … as far as B.1.1.7 is concerned, the kind of disaster we have seen in the United Kingdom and Ireland can occur?” he asks.
The data is not reassuring. The best advice from Danish scientists is that B.1.1.7 spreads 1.55 times faster than previous variants, says Holten Møller. To prevent it from getting out of control, the country will have to stay in the lock – or even add new controls – until a large part of the population has been vaccinated. The prospect is so unattractive that some epidemiologists say Denmark should consider an alternative: reopen as soon as the most vulnerable people are vaccinated, even if it means a huge increase in cases.
Denmark reported B.1.1.7 within its borders in December 2020, shortly after the United Kingdom notified the world, and has since launched an already impressive virus-tracking operation. Mads Albertsen, a researcher of bacterial genomes at the University of Aalborg, leads a team that has followed up virus genomes of more than half of all COVID-19 patients so far this year and hopes to reach 70% soon.
It was clear in early January that B.1.1.7 approximately doubles in frequency every week, says Lone Simonsen, an epidemiologist at Roskilde University. At that time, Denmark had already closed schools and restaurants; to combat the new threat, the exclusion was intensified by, for example, reducing the number of people allowed to gather from 10 to five and doubling the recommended distance between people from 1 to 2 meters. This, according to the most recent estimate, helped bring the overall reproduction number (R) to a healthy 0.78. But B.1.1.7 still has an estimated R of 1.07; in other words, it grows exponentially. Meanwhile, the proportion of COVID-19 cases infected with the variant increased from less than 0.5% in early December 2020 to 13% at the end of January.
A new virus collects steam
Previous SARS-CoV-2 variants are declining rapidly in Denmark (above), but B.1.1.7 are increasing (below).
(GRAPH) V. ALTOUNIAN /SCIENCE; (DATA) STATE SERUM INSTITUTE
The country can take further steps, such as urging people to work from home as much as possible and improve contact tracing, which becomes easier as the numbers dwindle. The implementation of rapid tests can also help, and more can be done to encourage patients to isolate them, says Michael Bang Petersen, a political scientist at Aarhus University; At present, half of those who have a positive test do not isolate.
By doing more, Denmark could still get rid of B.1.1.7 and fend off a third wave, says Andersen, pointing out that case numbers are declining in the UK, where B.1.1.7 now dominates: ‘It can be done, but it takes a lot of effort. (He says Denmark should try to end the epidemic, according to New Zealand style, completely through aggressive measures and border closures.)
Others are not convinced that the tide can turn. The decline in the UK may be partly due to the fact that so many are already infected and no longer susceptible, says Viggo Andreasen, a model from Roskilde. At best, Denmark can push R for the variant just below 1, he says, which will lead to a very slow decline, though better weather could help by April.
So far, the public has accepted the message from the government that the closure should remain despite the declining business, says Petersen, who is coordinating a project to investigate how the government and the public are responding to the pandemic: ‘What was incredible during January is that the numbers dropped significantly, but at the same time people reduced their contacts even further. “But it will be difficult to keep up as time goes on,” he says. “There is a lot of pressure on the government to reopen the country,” adds Thea Kølsen Fischer, a virologist at the University of Copenhagen. In a small first step, the government reopens schools for children in first to fourth grade on 8 February.
Simonsen says the cost of extending the lockout for many more months could be too high. Instead, Denmark should consider opening up as soon as people over 50 and other vulnerable groups are vaccinated – an effort that is underway. Reopening may cause a sharp increase in cases among unvaccinated, but few are likely to die. At that point, society may think more of SARS-CoV-2 as the flu, which also kills healthy young people, she says: “We are not closing birthday parties for this.”
Andreasen disagrees. The adoption of a new boom could have been a good strategy before other countries see variants emerge that seem to partially evade human immunity. More infections increase the risk of further viral evolution, he says. “It’s a nasty mix to have a population where half the population houses the virus, and the other half is like a big experimental vessel for the virus to learn how to escape immunity.”
Letting go of the virus would have another disadvantage, says Devi Sridhar, a global health scientist at the University of Edinburgh: more people with mild infections can develop long-term health problems. “Given what we know about long COVID and the associated diseases we can see,” says Sridhar, “I just think the risks are great with it.”