(Paris) The announcement last Friday had the effect of a bomb: the variant of the COVID-19 virus that is overwhelming the British hospital system is not only more contagious, but is also said to be more deadly. What is it?
Data that conclude that the “English variant” is 30-40% more lethal than the classic virus is limited, the scientists note, as concern grows in dozens of countries where the 50-70% more transmissible variant has now been detected.
What has changed
Two separate studies from the London School of Hygiene and Tropical Medicine (LSHTM) and Imperial College London linked data of positive cases detected out of hospital with mortality data. Using slightly different methods, they both estimate the additional risk of dying from the new variant to be around 30%.
Other studies from the University of Exeter and the public health agency Public Health England have found even higher risks.
Based on these results submitted to it, NERVTAG, the group that advises the UK government on respiratory viruses, indicated that there was a “realistic possibility” that infection with this variant was associated with a higher risk of mortality.
The greater contagiousness of this variant, called B.1.1.7 or VOC 202 012/01, had already caused concern across the world as health systems are already strained: the greater the number of infected people. is important, the more the number of patients suffering from severe forms increases, as does the number of deaths.
“Unfortunately, it seems that this virus is both”, more contagious and perhaps more deadly, summed up Monday at a press conference John Edmunds, of the LSHTM. “Unfortunately, the situation is really getting worse. ”
Are the data reliable?
There are uncertainties in the data, according to researchers who hope things will be clearer in a few weeks.
Even though the results are “statistically significant,” the studies were based on positive cases outside the hospital. However, most of the patients who subsequently died were tested positive only on arrival at the hospital, noted John Edmunds. And hospital data is not yet available.
According to NERVTAG, this gap could explain why studies have not found an increased risk of hospitalization in people infected with the new variant, which seems to contradict a greater severity of the disease.
The searches covered only 8% of total deaths over the period analyzed and the results may “not be representative of the entire population,” the group also noted.
Why more deadly?
Although more studies are needed, the researchers hypothesize that the greater lethality is linked to the same mutations as the greater transmissibility.
In particular, a mutation in the spicule or spike protein of the virus, this point on its surface which allows it to attach to the ACE2 receptor of human cells to penetrate them, plays a key role in viral infection. .
“If it is able to spread more quickly through the lungs in this way, it could accelerate the progression of disease and inflammation, which progresses faster than the body can cope with,” explained Peter Horby, head of NERVTAG and specialist in emerging infectious diseases at the University of Oxford.
“The virus may not have evolved to become more deadly as such, but it could have evolved to develop faster or better”, for his part indicates to AFP Bjorn Meyer, virologist at the Institute Pastor in Paris.
What impact on treatments?
There is “no evidence” that the treatments used would work less well against the British variant, according to Peter Horby, head of the Recovery clinical trial which concluded that the corticosteroid dexamethasone was effective against severe forms.
Corticosteroids “should work just as well because it’s not related to the virus, it’s related to the host response,” he said.
As for vaccines, the first elements are rather reassuring.
Thus, according to preliminary results from researchers from British and Dutch universities, the antibodies of former patients with COVID-19 largely make it possible to neutralize the English variant.
Pfizer / BioNTech and Moderna, based on preliminary studies, also ensured that their vaccines would still be effective against the variant.
More widespread, therefore weaker?
Scientists warn against the idea that greater contagiousness of the virus would necessarily make it less infectious.
With its current virulence – serious forms for a minority of infected people – it is already “very good at being transmitted”, indicates to AFP Emma Hocroft, epidemiologist at the University of Bern.
So there is no reason to “seek to become less serious,” she continues, stressing that viruses such as measles or HIV have remained as dangerous despite their spread.
Whatever the uncertainties on the studies on the lethality of the English variant, they must at least dispel the idea that it could become less virulent, insisted on his side Graham Medley, of the LSHTM.
“It obviously hasn’t turned into a more benign virus,” he said.