Two studies, published Tuesday, claim that the ‘British’ variant of the coronavirus does not cause more severe forms of Covid-19, contrary to the conclusions of previous research, but confirm that it is much more contagious than the strains previous ones.
The authors of the first study, published in Infectious Diseases The Lancet, analyzed the data of 341 Covid patients hospitalized in London between November 9 and December 20, in the midst of the emergence of the 501Y.V1 variant, now dominant in much of Europe.
New research article: Genomic characteristics and clinical effect of emergence # SARS-CoV-2 Line B.1.1.7 in London, United Kingdom: whole genome sequencing and hospital cohort study https://t.co/RpOwtB9ECs “We did not identify any association of the variant with severe disease …”
– Infectious Diseases The Lancet (@TheLancetInfDis) April 12, 2021
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.
The researchers, on the other hand, showed that samples from patients infected with the variant contained, on average, a greater quantity of virus, indicating a higher transmissibility.
A second study which confirms the first with a different methodology
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 “British” variant 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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Critics of the first study
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 articles, which associate the ‘British’ variant with a higher likelihood of death and severe forms. of Covid.
They note that the study published in the Lancet has the advantage of having used complete sequencing of the virus in its analyzes but that its “reassuring” conclusion must “be confirmed by larger studies”.
“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. It “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 adds.