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The news that the strain of coronavirus sweeping across Britain could be deadlier and more transmissible has raised new concerns about the variant which has spread to dozens of countries.
Initially, UK experts said their evidence suggested the new strain circulating in the UK – one of many to have emerged internationally in recent months – was between 50% and 70% more transmissible.
On Friday, however, the government said the new variant could also be 30-40% more deadly, although it stressed the assessment was based on scarce data.
What changed?
In mid-January, two separate studies from the London School of Hygiene and Tropical Medicine and Imperial College London were presented to the UK Advisory Group on New and Emerging Respiratory Virus Threats (NERVTAG).
They linked data from people who tested positive for the virus in the community – rather than in the hospital – with data on deaths and found an approximately 30% increase in the risk of death associated with the new strain.
The groups used slightly different methods, but both matched people with the new variant to those with the older variants, taking into account other variables such as age and location and controlling for hospitals. under pressure.
Other studies from the University of Exeter and Public Health England have also found higher deaths and both have resulted in even higher numbers.
Based on these analyzes, NERVTAG said there was “a realistic possibility” that infection with the new variant was associated with an increased risk of death compared to previously circulating variants.
The increased transmissibility associated with the variant was already alarming, as the more people the virus infects, the more people will suffer from serious illness and risk of death.
“Unfortunately, it looks like this virus could be both ‘more infectious and potentially more deadly,’ John Edmunds, professor at LSHTM’s Center for Mathematical Modeling of Infectious Diseases, told a press briefing on Monday.
“So this is really a turning point for the worse unfortunately,” he said.
How reliable are the results?
The researchers said there were still uncertainties in the data and said the picture will become clearer in the coming weeks.
Edmunds said the results were “statistically significant”.
But he said that while the studies used information from people tested in the community, most people who die from COVID-19 go straight to the hospital and are tested there.
Researchers do not yet have this information about the hospital.
The NERVTAG said this delay in data could be the reason why studies did not find evidence of an increase in hospitalizations of people with the new variant, which appears to contradict the results of a increased severity of the disease.
He also said that the mortality data used in the research covered only 8 percent of the total deaths during the study period, and the results “therefore may not be representative of the total population.”
Why more deadly?
Researchers believe it could be the same set of mutations that made it more infectious – although all stress is more studied.
One mutation in particular increases the virus’s ability to cling more strongly to human cells, and NERVTAG director Peter Horby, professor of emerging infectious diseases at the University of Oxford, said evidence suggests that means that ‘it might be easier to get infected.
“If it is then able to spread between cells much faster in the lungs, it can increase the rate of disease and the rate of inflammation, which can then progress faster than your body can respond, which could explain the two characteristics of the virus, “he said.
Bjorn Meyer, a virologist at the Institut Pasteur in France, told AFP the problem could be the viral load.
“The virus may not have evolved to be more lethal as such, but it may have evolved to grow larger or better, which could cause more damage in a patient in general,” he said. -he declares.
Does this affect the treatments?
Horby, who is also leading the recovery trial – which identified the steroid dexamethasone as effective for critically ill hospital patients – said there was “no evidence” that the treatments would work less well.
Anti-inflammatory drugs such as dexamethasone “should also work because they are not related to the virus, they are related to the host response,” he said.
Horby said overall improvements in therapies and treatments – including things like better strategies for hospital breathing support – have lowered case fatality rates since the first wave and may even “make up for any difference with that. new variant “.
As for vaccines, a preliminary study conducted this month in Britain and the Netherlands found that the variant would not be able to escape the protective effect of current vaccines.
Pfizer / BioNTech and Moderna also published preliminary research suggesting their vaccines are still effective against the strain.
Don’t viruses weaken as they spread?
Scientists sought to challenge the belief that the virus would become less virulent as it matured to become more infectious.
The virus that causes COVID-19 is already “very good at its transmission job,” said Emma Hocroft, epidemiologist at the University of Bern.
“So I don’t think we can make that assumption that it wants to be any less harsh. I don’t want to downplay that it’s serious for a lot of people, but for the majority of people it’s okay.” , did she say. AFP.
She said the ability to transmit before she kills was “a really low bar,” citing diseases like measles and HIV that have remained so dangerous.
Graham Medley, professor of infectious disease modeling at LSHTM, told Monday’s press conference that despite uncertainties in new studies on the new UK variant, they should dispel the idea that it will become less virulent.
“This is certainly not the case if it is a more benign virus,” he said.
© Agence France-Presse
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