A shopping street in Copenhagen, Denmark, during the blockade in January. Keeping COVID-19 variant B.1.1.7 at a distance may require additional control measures, say the scientists.
EMIL HELMS / Ritzau Scanpix / AFP via Getty Images
By Kai Kupferschmidt
Science‘s COVID-19 reports are supported by the Heising-Simons Foundation.
At first glance, the curve of COVID-19 infections in Denmark looks very reassuring. A national blockade caused the numbers to plummet from more than 3,000 daily cases in mid-December 2020 to just a few hundred now. But don’t be fooled. “Sure, the numbers look good,” says Camilla Holten Møller, of the Statens Serum Institute, who heads a group of experts who model the epidemic. “But if we look at our models, this is the lull before the storm.”
This is because the graph actually reflects two epidemics: one, decreasing rapidly, which is caused by older variants of SARS-CoV-2, and a smaller, slow-growing outbreak of B.1.1.7, the variant first recognized in the England and now taking big third wave of the pandemic there. If B.1.1.7 continues to spread at the same pace in Denmark, it will become the dominant variant later this month and cause the overall number of cases to increase again, despite the blockade, Holten Møller says. “It’s a complete game changer.”
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The same is probably happening in many countries without being noticed. But a major virus sequencing effort has enabled Denmark, a country of 5.8 million people, to monitor the emergence of the new variant COVID-19 more closely than any other country. “All eyes are on Denmark now,” said Kristian Andersen, an infectious disease researcher at Scripps Research who advises the Danish government. “When it comes to B.1.1.7, is there a way to … can we avoid the kind of calamity we saw in the UK and Ireland, for example?” he asks.
The data is not reassuring. The best guess for Danish scientists is that B.1.1.7 spreads 1.55 times faster than previous variants, says Holten Møller. To prevent this from getting out of control, the country will have to remain confined – or even add new control measures – until a large part of the population is vaccinated. This prospect is so disagreeable that some epidemiologists say that Denmark should consider an alternative: reopening as soon as the most vulnerable people are vaccinated, even if it means a further increase in cases.
Denmark reported B.1.1.7 within its borders in December 2020, shortly after the United Kingdom alerted the world, and has since stepped up an already impressive virus sequencing operation. Mads Albertsen, a bacterial genome researcher at Aalborg University, leads a team that has sequenced virus genomes of more than half of all COVID-19 patients so far this year and expects to reach 70% soon.
It became clear in early January that B.1.1.7 was almost doubling in frequency each week, says Lone Simonsen, an epidemiologist at the University of Roskilde. At that point, Denmark had already closed schools and restaurants; To combat the new threat, the blockade was reinforced by cutting the number of people who can meet from 10 to five, for example, and doubling the recommended distance between people from 1 to 2 meters. This helped to bring the general reproductive number (R) to healthy 0.78, according to the most recent estimate. But B.1.1.7 still has an estimated R of 1.07; in other words, it is growing exponentially. Meanwhile, the proportion of COVID-19 cases infected with the variant has increased from less than 0.5% in early December 2020 to 13% in late January.
A new virus gains strength
Previous variants of SARS-CoV-2 are declining rapidly in Denmark (top), but B.1.1.7 is on the rise (bottom).
(GRAPHIC) V. ALTOUNIAN /SCIENCE; (DATA) STATENS SERUM INSTITUTE
The country could take other measures, such as requiring people to work from home when possible and improving contact tracking, which becomes easier as the number decreases. Rapid test implementation can also help, and more can be done to encourage patients to isolate themselves, says Michael Bang Petersen, political scientist at Aarhus University; Currently, half of those who receive a positive test are not isolated.
By doing more, Denmark can still get rid of B.1.1.7 and avoid a third wave, says Andersen, who points out that the number of cases is falling in the UK, where B.1.1.7 now dominates: “It can be done, but it requires a huge amount of effort. ”(He says Denmark should try to end its New Zealand-style epidemic through aggressive measures and border closures.)
Others are not convinced that the tide can change. The drop in the UK may be partly due to the fact that many have already been infected and are no longer susceptible, says Viggo Andreasen, a modeler for Roskilde. At best, Denmark could push R into the variant just below 1, he says, leading to a very slow decline – although better weather in April may help.
So far, the public has accepted the government’s message that the blockade needs to remain in place despite declining cases, says Petersen, who coordinates a project to study how the government and the public are responding to the pandemic: “What was incredible during January is that the numbers have dropped substantially, but at the same time, people have further reduced their contacts. ”But that will be difficult to sustain over time, he says. “There is enormous 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 is reopening schools for children from first to fourth grade on February 8.
Simonsen says the cost of extending the blockade for many more months may be too high. Instead, Denmark should consider opening up once people over 50 and other vulnerable groups have been vaccinated – an effort that is underway. The reopening may trigger a sharp increase in cases among those not vaccinated, but probably few would die. At that point, society could start thinking about SARS-CoV-2 more like the flu, which also occasionally kills healthy young people, she says: “We don’t close birthday parties because of that.”
Andreasen disagrees. Accepting a new outbreak may have been a good strategy before other countries saw variants emerging that seem to partially escape human immunity. More infections increase the risk of further viral evolution, he says. “It is an unpleasant mix to have a population in which half the population is home to the virus and the other half is like a large experimental container for the virus to learn how to escape immunity.”
Letting the virus go 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. “Considering what we know about long COVID and the associated morbidity, we can see,” says Sridhar, “I think the risks are high with that.”