A study carried out by researchers at the Statens Serum Institut (SSI) in Denmark show evidence that the Ômicron sub-variant BA.2 can cause reinfection of people cured of Covid-19 within 20 days.
The result explains why people infected with the coronavirus in January, when Brazil went through the first wave of the Ômicron variant, are falling ill again.
A report of Oswaldo Cruz Foundation (Fiocruz), published on Monday (6/13), shows that the BA.2 lineage has become dominant in Brazil, replacing BA.1. There was also the detection of other strains with greater transmission potential in the country. The Fiocruz Genomic Network paper is based on samples from May 20 to June 2.
“How long are we protected after a Covid infection? For Delta, protection averaged three months. With Ômicron and the new subvariants, that has changed. There are reports of reinfection within 20 days,” medical epidemiologist Denise Garrett wrote on Twitter, sharing the Danish research.
In the study, published at the end of February on the platform medRxivresearchers in Denmark had access to samples from approximately 1.8 million cases of coronavirus infections – regardless of variant – in the country from November 22, 2021 to February 11, 2022.
Using whole-genome sequencing of the virus, they selected BA.2 reinfection cases within 20-60 days of initial BA.1 infections, during which time both subvariants emerged and became dominant in Denmark. .
Of a total of 187 cases of reinfection, 47 were identified by BA.2 shortly after infection with BA.1, especially among youth – with an average age of 15 – and unvaccinated. Most developed benign disease, without the need for hospitalization; there were also no death reports.
“We have evidence that re-infections with the BA.2 subvariant can indeed occur shortly after a BA.1 infection, causing mostly mild disease in young unvaccinated individuals, but they are rare,” they said. concluded the researchers.
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