Two studies published Tuesday affirm that the "British" variant of the coronavirus does not cause more serious forms of Covid-19, contrary to the conclusions of previous research, but confirm that it is much more contagious than the previous strains.
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The authors of the first study, published in
The Lancet Infectious Diseases
, analyzed data from 341 Covid patients hospitalized in London between November 9 and December 20, with the emergence of the 501Y.V1 variant, which is now largely dominant. from Europe.
58% of them were infected with this variant, also known by its lineage name, B.1.1.7, and 42%, with other strains.
36% of patients in the first group became seriously ill or died, compared to 38% in the second group, suggesting that B.1.1.7 is not associated with greater severity.
However, the researchers showed that samples from patients infected with the variant contained, on average, a greater quantity of virus, indicating a higher transmissibility.
The second study, published in
The Lancet Public Health
, analyzed data from nearly 37,000 UK users of a mobile application designed to report their symptoms of Covid, who were diagnosed positive between September 28 and December 27.
From the number of people who reported symptoms each week in a given area, she concluded that the
had a reproduction rate 1.35 times higher, that is to say that each infected patient infected in average 35% more people than with previously circulating strains of the virus.
On the other hand, the variant did not cause more serious symptoms or a greater probability of having prolonged symptoms ("long Covid").
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In a commentary on the first study, three researchers from the National Center for Infectious Diseases (NCID) in Singapore point out that its findings contrast with three previous papers, which associate the 'British' variant with a higher likelihood of death and severe forms. of Covid.
They note that the study published in the
has the advantage of having used complete sequencing of the virus in its analyzes but that its
"be confirmed by studies of larger scale"
“This study focuses on the clinical results of a group of people already hospitalized with Covid-19,”
observes epidemiologist Nicholas Davies, however, cited by the British Science Media Center.
“does not contradict the elements already gathered by previous studies”
, which tend to show that
“infection with B.1.1.7 is globally associated with a higher risk of mortality, hospitalization and admission to hospitals. emergencies among all individuals tested positive for Sars-CoV-2, ”he