What we do and don’t know about new COVID mutations

The emergence of two new variants of SARS-CoV-2 in the United Kingdom and South Africa has raised widespread concern that the virus could be much more infectious. This is what we know and don’t know about mutations.

what are they?

All viruses mutate when replicated to adapt to the environment.

Scientists have tracked multiple mutations in SARS-CoV-2, the virus that causes COVID-19, since its emergence in China in late 2019.

The majority of mutations did not substantially alter either the pathogenicity or the infectivity of the virus.

However, one mutation (variant B117, which, according to Imperial College London, is likely to have emerged in southeast England in September), is currently being detected in countries around the world, including the United States, France, and India.

Another subspecies 501.V2 was detected in South Africa in October and has since spread to several countries, including the United Kingdom and France.

Both have multiple mutations in the virus, especially the spike protein (the part of the virus that latches into human cells and helps spread).

Specifically, the mutant version has a modified receptor-binding domain known as N501Y, which is located on the viral protein spike and facilitates access to the ACE2 receptor in human cells.

This can make the mutated version more infectious than other strains.

The European Center for Disease Control and Prevention states that there is “no clear link” between enhanced ACE2 binding and increased transmissibility, but “it is plausible that such a link exists.”

Are they more contagious?

Indeed, some recent studies (not yet peer-reviewed) have concluded that the UK variant of SARS-CoV-2 is likely to be much more contagious than other strains.

NERVTAG Expert Committee Advising the UK Government Disease management The new mutation was estimated to be more contagious than 50 to 70 percent.

The team at the London School of Hygiene and Tropical Medicine (LSHTM) agrees, with experts increasing transmission rates in the 50-74 percent range.

Last week, researchers at Imperial College London published the results of a study on the sequences of thousands of SARS-CoV-2 genes found in the United Kingdom between October and December.

They found that the new variant had “substantial infectious benefits” and that the reproductive rate was 0.4-0.7 higher than that of the unmutated virus.

Preliminary studies on South African variants have also concluded that they are more contagious than regular SARS-CoV-2.

Early data seems to confirm that the two new versions are more contagious, but experts warn.

Bruno Coignard, head of infectious disease at Sante Public France, the French health authority, told AFP that the spread of British variants was due to a “combination of factors.”

“These are related not only to the characteristics of the virus, but also to the preventive and control measures being taken,” he said.

Are they more dangerous?

Currently, there is no evidence to suggest that the mutated virus is stronger than normal.

However, given that a small but consistent proportion of COVID-19 patients require hospital care, increasing transmission rates alone poses major problems.

“Increased transmission rates ultimately lead to much higher incidence, and even at the same mortality rate, this represents significant pressure on the healthcare system,” says Coignard.

Adam Kucharski, an epidemiologist at LSHTM, said that a virus that is 50% more contagious poses a “much bigger problem” than a deadly virus.

In a Twitter thread, he has a COVID-19-like illness with a recall (R) of 1.1, each patient on average infects the other 1.1, with a mortality rate of 0.8%, within 129. He explained that people are expected to die. Moon.

If the mortality rate increases by 50%, the number of deaths will increase to 193.

However, more contagious mutants increase exponentially, resulting in 978 deaths in diseases with a 50% higher infection rate.

Arnaud Fontanet, an epidemiologist at the French Science Council, admitted on Monday that the new British variant was “very concerned now.”

Early studies also concluded that British varieties were significantly more contagious among adolescents. And it raises the question of whether to keep the school open.

An LSHTM study concluded that a blockade similar to that seen across the UK in November was insufficient to stop the spread of new variants “unless elementary schools, middle schools and universities were closed”. It was.

Does the vaccine still work?

As vaccination campaigns are underway around the world, is there any reason to be afraid that new mutations may not respond to vaccine hosts already on the market?

After all, the messenger RNA vaccine developed by Pfizer and Moderna tricks the body into recreating the viral peplomer (the exact part of the mutated pathogen in the new version).

The ECDC said it was too early to know if mutations would affect the effectiveness of the vaccine.

“Experts believe that current vaccines are effective against these strains,” Henry Walk of the US Centers for Disease Control and Prevention told reporters last week.

However, on Monday, François Barrow, a professor of computational systems biology and director of the Institute of Genetics at University College London, said a South African subspecies spike protein mutation “viruses provided by previous infections or vaccinations.” Helps avoid immune protection. “

BioNTech, a German vaccine developer, says it can develop new vaccines that work in mutant versions within 6 weeks, if needed.

What can you do about them?

Coignard said policymakers’ goal should be the “maximum delay” in their spread, but it is impossible to completely eradicate new viral variants.

“Efforts to delay the epidemic should reflect efforts made in the early stages of the pandemic,” the ECDC said in countries currently unaffected by the new mutations.

These include new testing and quarantine, contact tracing and limited travel, he said.

If you’re lucky, certain existing PCR tests can detect UK variants.

Therefore, Fontanet advocated “very active surveillance” through extensive testing.

“We are more careful about preventative measures to delay the spread of COVID-19 by wearing masks, at least 6 feet away from people who do not live with us, avoiding crowds, ventilating indoor spaces and washing our hands. You have to pay. “Walk said.

© 2021 AFP