A more contagious variant, which can cause re-infections. Brazilian and English researchers posted on February 25 the first detailed study on the Brazilian variant, not published at the time. According to their work, this variant called P.1 would have two advantages over the old strain of coronavirus: it would be more contagious and could cause re-infections.

Strong second wave, despite immunity

This study is based on observations made in Manaus, Brazil. This city was affected in the spring of 2020 by a very strong first wave of covid. Blood serological tests show that three-quarters of the population had then been infected with the “historic” strain of the coronavirus and had developed immunity, report the authors.

Despite this, the people of Manaus once again suffered a strong wave this winter, marked by a predominance of the P.1 variant that appeared in the region in November 2020.

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A risk of reinfection of 25 to 61%

The researchers produced models taking into account the genomic data of the viruses and the mortality data. First observation: the Brazilian variant would be between 1.4 and 2.2 times more transmissible than the old strain.

And second result: it seems to be able to escape the immunity conferred by a previous infection, causing a risk of reinfection that scientists estimate between 25 and 61%.

Effective vaccines?

For the moment, these are only preliminary data and the study has not been published in a scientific journal, but these results agree with epidemiological predictions already made on this variant.

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And as for the South African variant, the capacity of the Brazilian variant to escape immunity raises the question of the effectiveness of the vaccines available against this variant.

Studies to assess the actual efficacy of vaccines in response to the P.1 variant are urgently needed“insist the authors of the publication. Manufacturers have already deployed strategies to adapt their vaccines to variants. This is the case of Moderna, which is starting new clinical trials on a modified version of its vaccine , and Pfizer, which is testing the effectiveness of a third dose of its vaccine to strengthen immunity against variants.