The coronavirus variant is actually more transmissible, suggests a new study

A team of British scientists released a worrying study on Wednesday about the new variant of the coronavirus that is sweeping the UK. They warned that the variant is so contagious that new control measures, including the closure of schools and universities, may be necessary. Even that may not be enough, they noted, saying, “It may be necessary to speed up the launch of the vaccine a lot.”

a group of people walking down the street: A gazebo outside a bar in London's West End on December 15th.  The city went into Level 3 restrictions the next day.

© Andrew Testa for The New York Times
A gazebo outside a bar in London’s West End on December 15th. The city entered Level 3 restrictions the next day.

The study, released by the Center for Mathematical Modeling of Infectious Diseases at the London School of Hygiene and Tropical Medicine, has not yet been reviewed by a scientific journal. The study compares a series of models as predictors of data on infections, hospitalizations and other variables; other researchers are studying the variant in laboratory experiments to determine whether it is biologically distinct.

The study found no evidence that the variant was more deadly than others. But the researchers estimated it was 56% more contagious. On Monday, the British government released an initial estimate of 70 percent.

Bill Hanage, an epidemiologist at the Harvard School of Public Health TH Chan who was not involved in the study, said he provided a convincing explanation of the variant’s past and potential future.

“The overall message is solid and consistent with what we have seen from other sources of information,” he said in an interview. “This matters? Yes. Is there evidence of greater transmission? Yes. Will it have an impact in the coming months? Yes. All of these are, I think, very solid. “

The variant, which caught the attention of British researchers earlier this month, has spread rapidly across London and eastern England. It carries a set of 23 mutations, some of which can make it more contagious.

The study authors found more evidence that the variant does indeed spread more quickly than others. For example, they ruled out the possibility that it was becoming more common because the outbreaks started in places where people were more likely to come into contact with each other. The data recorded by Google, indicating the individual movements of cell phone users over time, did not show such a difference.

The researchers built different mathematical models and tested each one as an explanation for the spread of the variant. They analyzed which dissemination model best predicted the number of new cases actually confirmed, as well as hospitalizations and deaths.

The team then designed what the new variant would do in the next six months and built models that took into account different levels of restrictions. Without a more substantial vaccine launch, they warned, “cases, hospitalizations, ICU admissions and deaths in 2021 may exceed those in 2020”.

Closing schools by February could give Britain some time, the researchers found, but lifting these extra restrictions would cause a major recovery in cases.

Because of the higher transmission rate, the country will need a much larger percentage of the population to be vaccinated and to achieve collective immunity. To reduce peak load in ICUs, the researchers found, vaccination would need to jump to two million people a week, compared to the current rate of 200,000.

“You need to be able to get as many barriers to transmission as you can as quickly as possible,” said Hanage.

The researchers warned that their model was based, like any model, on a set of assumptions, some of which may be wrong. For example, the rate at which infected people die from Covid-19 may continue to fall as doctors improve care for hospitalized patients. Uncertainties remain as to whether the new variant is more contagious in children and, if so, how much.

Still, they wrote, “there is an urgent need to consider what new approaches may be needed to sufficiently reduce the continuous transmission of SARS-CoV-2”.

Alessandro Vespignani, director of the Network Science Institute at Northeastern University in Boston, who was not involved in the study, said of the new estimates: “Unfortunately, this is another plot twist.”

“While we were all rejoicing over the vaccine,” he added, “here is the possibility of a change in the epidemiological context that will make our next months much more complex and dangerous to navigate. Evidence is accumulating that the variant is more transmissible, and this implies that it will probably require an even greater effort to keep the spread under control. “

Dr. Hanage warned that the model had some shortcomings. The researchers assumed that everyone under the age of 20 had a 50 percent chance of spreading the disease. While this may be true for younger children, said Hanage, it is not for teenagers. “This is the weakest part of their model,” he said.

However, he said, the study offered an important glimpse into the country’s possible futures. “It is not a forecast, it is not a forecast, it is not saying it will happen,” he said. “It means that if you don’t take it seriously, that’s the kind of thing that can easily happen.”

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Benjamin Mueller contributed reporting.

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