Why scientists think the UK version of Covid-19 could be more deadly

Initially, UK experts said evidence suggests that new strains prevalent in the UK (one of the international emergences in recent months) are 50% to 70% more contagious. I did.

However, on Friday, the government said the new variants could also be 30-40 percent deadly, although the government emphasized that the assessment relies on sparse data.

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――What has changed? —

In mid-January, two separate studies by the London School of Economics and Tropical Medicine and Imperial College London were submitted to the New Respiratory Virus Threat Advisory Group (NERVTAG) in the United Kingdom.

They associated data from people who tested positive for the virus in the community rather than in the hospital with mortality data and found that the risk of death associated with the new strain was increased by about 30%.

The group used a slightly different method, but both matched the people of the new variant with the people of the old variant by managing the hospitals under pressure, taking into account other variables such as age and location. I did.

Other studies by the University of Exeter and the UK Public Health Services also had high deaths, both with even higher numbers.

Based on these analyzes, NERVTAG states that there is a “realistic possibility” that infection with new mutants is associated with an increased risk of death compared to previously circulating mutants. I did.

The increased infectivity associated with the subspecies was already alarming, as more people are infected with the virus and more people are at risk of serious illness and death.

“Unfortunately, the virus seems to be highly infectious and potentially deadly,” John Edmunds, a professor at the Mathematical Model Center for Infectious Diseases at LSHTM, said at a press conference on Monday.

“So, unfortunately, it’s a serious shift in the wrong direction,” he said.

-How reliable are the findings? —

Researchers said the data are still uncertain and the situation will become clearer in the coming weeks.

Edmonds said the findings were “statistically significant.”

But he said the study used information from people tested in the community, but most people who died in Covid-19 went straight to the hospital where they were tested.

The researcher does not yet have the hospital information.

NERVTAG said the delay in this data may be the reason why the study did not find evidence of increased hospitalization for people with the new mutation. This seems to be inconsistent with the discovery of increased severity of the disease.

The mortality data used in the study covered only 8% of the total number of deaths during the study, and the results “hence may not represent the total population,” he said.

-Why is it more deadly? —

Researchers believe it could be the same set of mutations that made it more infectious-although all stress requires more research.

In particular, one mutation enhances the ability of the virus to latch strongly into human cells, and Peter Horby, head of NERVTAG, a professor of emerging infectious diseases at Oxford University, has evidence that it can be susceptible to infection. He said he suggested.

“If it can spread much faster between cells in the lungs, it may increase the rate of disease and inflammation, and it may progress faster than your body can react. No, so it may explain both characteristics of the virus, “he said.

Bjorn Meyer, a virologist at the Pasteur Institute in France, told AFP that the problem could be viral load.

“The virus may not have evolved to be more deadly in itself, but it may have evolved to grow more or less.

-Does this affect treatment? —

Hobby, who is also leading a recovery trial that identified the steroid dexamethasone as effective in critically ill inpatients, said there was “no evidence” that the treatment did not work.

Anti-inflammatory drugs such as dexamethasone “should work as well because they are not related to the virus and to the response of the host,” he said.

Hobby said overall improvements in treatments and treatments, including better strategies for hospital respiratory support, reduced case fatality after the first wave and “offset the difference with this new mutant.” You can even do that.

In terms of vaccines, this month’s preliminary study from the United Kingdom and the Netherlands found that this variant could not avoid the protective effects of current vaccines.

Pfizer / BioNTech and Moderna also published early studies suggesting that their vaccine is still effective against strains.

-Will the virus weaken as it spreads? —

Scientists are trying to challenge the belief that as a virus evolves to become more infectious, it becomes less virulent.

Emma Hocroft, an epidemiologist at the University of Bern, said the virus that causes Covid-19 is already “very good at its job of infecting.”

“So I don’t think we can make this assumption that it’s not that strict. I don’t want to downplay it as strict for many, but it’s not so strict for most people,” she said. AFP.

She said her ability to communicate before it was killed was a “really low standard” and that diseases like measles and HIV remained dangerous.

Graham Medley, a professor of infectious disease modeling at LSHTM, said at a press conference Monday that the idea of ​​reduced toxicity needs to be dispelled despite the uncertainty of new research on new variants in the UK. It was.

“This is not a benign virus,” he said.