Covid-19: should we be worried about the variants of the coronavirus?

This is the news that worries the scientific community, health authorities and governments. Several variants of the coronavirus responsible for Covid-19 have been detected around the world, including the variant from the United Kingdom, the variant from South Africa and the Brazilian. Are they more dangerous than the initial strain? What do they have in common?  

What are the variants detected in the world?

As of January 19, the health authorities are known:

• The British variant so called because detected for the first time in the United Kingdom;
• The South African variant called 501Y.V2 (or 501.V2) discovered last October by South African researchers;
• The Amazonian or Brazilian variant appeared in Brazil but discovered for the first time in Japan. 

The British variant "VOC 2021"

It would be more contagious

A new variant of the SARS-COV-2 coronavirus was discovered in the United Kingdom and reported to the WHO on December 14, 2020. It would explain that the transmission is more important in parts of the South East of England, inform the 'AFP and the BBC on December 14, 2020. For the Secretary of State for Health, Matt Hancock, it could play a role in the "exponential spread of the virus in the south-east of England", without knowing "in what measure ". According to the latest data, the variant is believed to be responsible for more than 50% of cases in the south-east of England from October to December 2020.

Baptized "VUI-2020-12-01" then renamed "VOV 2021", this variant includes several mutations (no less than 24 changes compared to the initial virus) including the 614G mutation already observed by American scientists. These mutations would give the virus greater contagiousness, especially in children. 

According to the British health authorities, the R0 which represents the capacity of transmission of the virus from one person to another would be increased by +0.4 compared to other viruses,  "with a 'moderate' increase in the viral load estimated from RT-PCR values ​​". 

It could be linked to more serious forms than the initial virus

At present, according to studies, the British variant does not appear to give more serious forms or fatal complications than the "classic" coronavirus. But on January 22, Prime Minister Boris Johnson said this virus appeared to be not only more contagious, but also more deadly: “ It also now appears that there is evidence that the new variant, the variant that has been identified for the first time in London, and in the south-east (of England), may be linked to a higher degree of mortality"For men in their sixties, the risk of mortality reaches 13 to 14 in 1,000 with the new variant, against 10 in 1,000 with the previous form of the virus, compared the government's scientific adviser, Patrick Vallance But a lot of uncertainties remain around these figures and the WHO has not confirmed these data. " We do not see so far (...) that the disease is more deadly. What we are finding is that if more people are infected, more people will get very sick, and if more people get very sick, more people will die, "the director in charge of health issues said on the same day. health emergency at the World Health Organization, Michael Ryan during a press briefing.

The South African variant "501.V2"

It would be 1.5 times more contagious

Last October, a new variant different from that of Great Britain was identified by a team of South African researchers and reported on December 18, 2020 to the WHO. It has been observed in South Africa in the provinces of the Eastern Cape, Western Cape and KwaZulu-Natal. 

It seems that it, too, is more contagious than the classic coronavirus. According to South African experts whose comments were repeated by AFP on January 18, this variant is 1.5 times more contagious than the initial strain. It is " 50% more transmissible ", but "there is no indication that the new variant is more severe, " said Prof. Salim Abdool Karim, epidemiologist and co-chair of the scientific committee at the South African Ministry of Health. His words are based on data collected in outbreaks of the southern African country. 

It has the same N501Y mutation as the UK variant

"The variant in South Africa may give the impression of being the same as the one found in Britain because its mutations are similar, but it is different"  assured American epidemiologist Maria Van Kerkhove , responsible for the Covid-19 file at the  WHO , December 21, 2020.

Among their common points, the mutation called N501Y, which we do not yet know if it could explain that the South African variant is more contagious than the initial strain. 

The Brazilian or Amazonian variant

It was discovered in Japan

This new variant was detected in Japan on January 2, 2021 in four travelers from the state of Amazonas in Brazil. At present, it has not been observed in other countries of the world.

Very little data is available on this new variant. As the virologist Vincent Maréchal indicates to La Voix du Nord , " everything is still under study for the Brazilian (...)". 

As a precaution, the United Kingdom has banned arrivals from South America and Portugal on its territory. Transport Minister Grant Shapps said the decision was made on the basis of " evidence for a new variant in Brazil " and explained that Portugal was included in the restriction measures because of " its important links with Brazil. ". 

It carries some of the same mutations as the other two variants

Twelve mutations were observed on the Brazilian variant, two of which were common, one on the British variant and the other on the South African. Could they be responsible for greater contagiousness? For now, the answer is difficult to give, for lack of studies. " It is not yet certain, but it is very possible, because we have observed many mutations in the Spike protein (which allows the virus to enter cells, editor's note), which have already been associated to this greater potential for transmission of the virus, "remarks Felipe Naveca in an interview with AFP. 

New variants, a danger for anti-coronavirus vaccines?

It depends on the mutations present on the variant, according to some specialists. As stated by the WHO, " laboratory studies are underway to determine whether these variant viruses have different biological properties or modify the efficacy of the vaccine ." 

BioNTech and Pfizer laboratories have ensured that their vaccine was effective against the N501Y mutation common to the British and South African variants. " With the current state of our knowledge, experts believe that current vaccines will be effective against these variants," said Henry Walke of the US Centers for Disease Prevention and Control (CDC) recently. Note, however, that the study on which they are based does not cover all the mutations present in these variants: it is therefore not sufficient to conclude that the efficacy of the vaccine will be the same as against the classic virus.

Moderna's vaccine against Covid-19 remains effective against variants of the coronavirus , notably the British, but "a reduction by six"  in the levels of antibodies against the South African variant (B.1.351) has been observed, reports RelaxNews . "Despite this reduction" , the levels of antibodies  "remain above what is expected as necessary to provide protection" , wanted to reassure Moderna in the press  release . "But as a precaution, (...) we are testing a candidate (vaccine)"  against the South African variant, "to determine if it would be more effective in increasing the levels (of antibodies) against that variant. and D'   , he added. A phase 1 study on this new formula, called mRNA-1273.351, will be launched in the United States. It could be used to boost protection "in combination" with other vaccines, according to Moderna. 

Second lead: Moderna has also decided to launch  trials aimed at testing an additional dose of its already existing vaccine. 

Which of its variants is the most resistant to the immune system? 

A mutation called E484K present on the South African variant worries some specialists. It is suspected of helping this variant  "to bypass the immune protection conferred by a previous infection or by vaccination" , explained Monday, January 11, Professor François Balloux, of University College London, cited by the British organization Science Media Center. 

Asked by Doctissimo, Prof. Anne-Claude Crémieux, infectious disease doctor, explains that  “E484K, identified in the laboratory, has been linked to a decrease or even resistance in the serum of convalescents, that is to say in the blood of people who have been infected with the non-mutant strain and have developed antibodies. The fact that this mutation has been observed in the laboratory as being able to have an impact on the neutralization of convalescent serum is of particular concern. What will be the precise consequences on the vaccine? We wait to see ... It's a real question. Even if all virologists agree that all vaccines produce a lot of antibodies, we would prefer to have the results ” . 

The first mutations observed at the start of the epidemic

Between the discovery of the coronavirus in China and its emergence in the world, a mutation has already been spotted by American scientists. The first researchers to shed light on this thesis are those of the Los Alamos National Laboratory managed by the University of California in the United States. According to them, the strain of the SARS-COV-2 coronavirus present in Europe and the rest of the world is not the same as that which plagued the first days of the epidemic in China. This strain appeared in February in Europe, which has dominated the world since mid-March, would present a mutation and would be more contagious. 

In addition to infecting individuals more quickly, it would make people more vulnerable to a second infection , continue the authors of the study published on the site BioRxiv 1 , used by researchers to share their work before their examination by their peers. 

To arrive at this hypothesis, the scientists relied on a computer analysis of more than 6,000 coronavirus sequences from around the world collected by the Global Initiative for Sharing All Influenza Data, a public-private organization in Germany. They studied the Spike (S) protein that allows SARS-CoV-2 to infect cells in the human body. “ To date, we have identified fourteen mutations in Spike that accumulate, ” write the authors who explain that they focused on a mutation called D614G . “ When viruses carrying this mutation enter a population, they quickly start to take over the local epidemic, so they are more transmissible.”, Says study leader Bette Korber, a computer biologist in Los Alamos, on her Facebook page. “ The frequency of D614G is increasing at an alarming rate (...) compared to the original strain from Wuhan, which allows for faster spread ,” the study read. 

"It could be that this mutation is at the origin of the pandemic"

On November 24, 2020, more than 7 months after the publication of the Los Alamos National Laboratory study, the prestigious  New York Times was  already reviving the debate . " While the coronavirus was sweeping the world, it detected random alterations in the genetic sequence. Like typos meaningless in a script, most of these mutations have made no difference in the behavior of the virus. But mutation towards the onset of the pandemic made a difference, many new findings suggest, helping the virus to spread more easily from person to person and making the pandemic more difficult to stop ", reads the report. 'article.

As the American journal explains,  new research supports the hypothesis of a mutation of SARS-CoV-2 , infecting people more easily than the original variant detected in Wuhan in China, the epidemic focus. For David Engelthaler, a researcher and geneticist at the Institute for Translational Genomics Research in Arizona, interviewed by the  New York Times , " in the end, it could be that  this mutation is the cause of the pandemic ." 

Indeed, a 3 study  published in the scientific journal  The Cell  found that the epidemic in UK communities spread faster when the virus contained the 614G mutation than through its Wuhan ancestor. However, while the disease appears to be more contagious, there is no scientific evidence that this change causes more severe symptoms or more deaths. 

This change would explain  the difficulty that countries encounter in stemming the epidemic . Kristian Andersen, American geneticist told the media: " Don't necessarily expect the enemy of two months ago to be the enemy you will have next time. "