Saturday, January 23, 2021

The UK is scaring everyone with its new covid-19 strain. Here’s what scientists know.

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The situation could turn out to be a false alarm. Sometimes virus variants seem to spread more easily, but are actually propelled by luck, like a super-spreading event.

Teams in the UK, and some overseas, are now rushing to conduct the lab experiments needed to demonstrate whether the new variant really infects human cells more easily and whether vaccines will stop it; these studies will involve exposing the new strain to the blood plasma of covid-19 survivors or vaccinees, to see if their antibodies can block the variant.

Viruses frequently mutate or develop small changes in their genetic code. Since the start of the pandemic, scientists have been sequencing samples of the coronavirus have followed these changes to understand how and where the pathogen has spread.

One of the reasons the strain was spotted in the UK could be because the country has aggressively pursued such “genomic epidemiology”. For example, UK laboratories have contributed 45% of the 275,000 coronavirus sequences deposited in the global GISAID database, according to a threat assessment note of the European Center for Disease Prevention and Control.

According to the COVID-19 Genomics Consortium UK, the coalition of labs that sequenced viruses, the variant was first spotted on September 20 in Kent and a day later in London.

Separate signature

While mutations in the coronavirus are seen all the time, the new variant has raised alarms as it emerged at the same time as a sharp and alarming increase in cases in the south-east of England, where the rate of d infection has quadrupled recently. Almost half of these cases were due to the new variant.

The genetic code of the variant has also caught the attention of scientists, for its difference. According to a preliminary characterization published on the site virological.org by the COVID-19 Genomics Consortium UK, the variant has a “distinct” genetic signature with “an unusually high number of genetic changes” especially in its spike protein, which the virus uses to invade cells, and which are more likely alter its function.

The mutations seen in the new variant have all been spotted previously, according to comments posted online by Francois Balloux, a computer biologist at the University of College London, but apparently not in this combination. They include one that increases the way spike proteins bind to human cells, another linked to escaped human immune responses, and a third adjacent to a biologically critical component of the pathogen.

So far in the pandemic, the virus spread variants tend to pick up one or two new mutations per month. British scientists say they are surprised to find a variant that has accumulated a unique pattern of more than a dozen changes in important genes, which they suggest are clues that the stain could be the result of evolutionary adaptation. adapt.

Dodge the immune response?

In the UK group’s preliminary report, Andrew Rambaut of the University of Edinburgh and colleagues say they believe the variant could have evolved inside an immunocompromised person who was chronically infected by the coronavirus. These people, in some cases, have received multiple cycles of treatment with antibodies and antiviral drugs. This could select for viruses that survive treatment.

If the new strain is able to “escape” the usual immune response, this may also explain why it is spreading faster, as it would also affect some survivors of covid-19 and therefore have more hosts to infect. According to British scientific reports, four of the roughly 1,000 people infected with the new variant previously had covid-19, although they were not able to say if that figure was unusual.

The idea that the covid-19 virus could evolve enough to infect people again, despite immunity to the original germ, wouldn’t come as a total surprise. Other coronaviruses, which cause the common cold, are known to re-infect people frequently, probably because of such a change in shape.

Viruses can also change significantly if they become established in another species – even zoo tigers can catch covids – and then return to humans. This was seen in Denmark, which this fall reported transmission of the covid virus between humans and mink and conversely, a situation deemed so dangerous that the country ordered that all mink on commercial fur farms be slaughtered.

Now the world will learn if it is possible to prevent the new variant from spreading. It won’t be easy. Existing forms of covid-19 are already spreading rapidly despite social distancing and masks. If the new variant is actually 70% easier to spread, it could soon become the dominant form of the disease.

Over the weekend, UK authorities were criticized for sounding the alarm bells over the new strain to justify strict lockdown measures ahead of Christmas, including stay-at-home orders for millions of people. But officials took to the air to encourage people to obey the restrictions. “The new variant is out of control and we have to get it under control,” Matt Hancock, Secretary of Health, told BBC. He urged his compatriots to “act like you have the virus”.



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