Writing.
The emergence of two variants of the SARS-CoV-2 virus in the United Kingdom and South Africa is of concern to the international community, as it is more contagious, according to initial data.
What are these options?
All viruses move, meaning they change when they reproduce.
SARS-CoV-2 has undergone multiple variations since its inception, but in general these have had no consequences. Some mutations, however, can help them survive, for example, if they reach a larger contagion.
Variant B.1.1.7, now called VOC 202012/01, was detected in the United Kingdom in November, after developing “probably” in September in the south-east of England, according to Imperial College From London.
After the rapid spread in that country, this variant was detected in dozens of other countries, from US to South Korea, passing through India, France and Denmark.
Most cases were imported from the United Kingdom, but some have no proven relationship with that country, as in the case of Denmark, with 86 patients identified.
The 501.V2 variant, now predominant in South Africa, was detected there in October and was found in other countries, such as the United Kingdom and France.
According to experts, the number of cases of both variants is still underestimated.
Both have several mutations, one of which, N501Y, affects the “peak” protein of the coronavirus, a peak that serves to bind to and penetrate the ACE2 receptor in human cells.
This mutation increases the virus’s ability to adhere to the ACE2 receptor. And, although “there is no clearly established relationship between adherence to ACE2 and higher transmission, it is possible that there is,” according to European Center for Disease Prevention and Control (ECDC).
More transmissible?
Several scientific studies, mainly based on model studies and not yet evaluated by other experts according to the scientific protocol, conclude that the British version is much more transmissible, confirming the initial assessment of the NERVTAG research group, which advises the British government. and who estimated the difference between + 50% and + 70%.
Thus, according to the calculations of the London School of Hygiene and Tropical Medicine (LSHTM), the British version would be 50-74% more contagious. For him Imperial College from London, which analyzed thousands of genomes of the SARS-CoV-2 virus, the capacity for contagion is 50-75% higher and the reproduction rate (R) is between 0.4 and 0.7 higher than the usual virus .
Preliminary findings on the South African variant also show increased transmission, but less data are available.
In the absence of conclusive results, some experts are cautious.
“You have to be careful. The incidence is a combination of factors that take into account the characteristics of the virus, but also the prevention and control measures applied” to fight covid-19, Bruno Coignard, director of infectious diseases, told AFP. from the French health agency Public health France.
More dangerous?
“No available information indicates that infections in these strains are more serious,” according to ECDC. But the risk “is high in terms of hospitalizations and deaths.”
And it is that “greater contagion ultimately equates to a much higher incidence and therefore greater pressure on the health system, although the lethality (variants) is the same,” according to Coignard.
A variant of SARS-CoV-2 the fact that it was “50% more transmissible would be a bigger problem than a 50% more deadly variant,” says British epidemiologist Adam Kucharski on Twitter, using a statistical demonstration: with a reproduction rate of 1.1, a mortality rate of 0.8% and 10,000 infected people, after a month would be 129 deaths. But if the contagion rate increased to 50%, the number of deaths would increase to 978.
On the other hand, early studies of the British version suggest that it is more contagious among young people under 20 than the usual strain, raising the issue of school closures.
The LSHTM study thus estimates that the measures taken in November during detention in the United Kingdom would not be effective in controlling the epidemic, “if schools, colleges and universities were not also closed”.
Do they affect the effectiveness of vaccines?
“At the moment, we do not have enough information to say that these variants pose a ‘risk to vaccine efficacy,'” ECDC estimates.
However, with the data available, “experts believe that current vaccines will be effective against these strains,” Henry Walke of the U.S. Centers for Disease Control and Prevention said Wednesday.
The German laboratory BioNTech, creator with Pfizer from the world’s first authorized covid-19 vaccine, he assured that, if necessary, he could provide a new product in “six weeks” to respond to a mutation.
How to deal with variants?
In the absence of the possibility to prevent the spread of these variants, the goal is to “delay” them as much as possible, according to Coignard.
ECDC recommends that affected countries take measures similar to those at the beginning of the pandemic, such as limiting travel and testing people in high-risk areas. It also calls for controlling the incidence of these variants, multiplying the sequencing of viruses.
Some tests PCR they can also suggest the presence of the British variant and then proceed with sequencing the sample, according to epidemiologist Arnaud Fontanet, a member of the scientific council advising the French government.
At the individual level, “we need to be even more rigorous with prevention measures,” according to Dr. Walke, referring to hand washing, wearing masks, and so on.