May 8, 2021


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A variant of the Brazilian virus escaping natural immunity

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The P.1 Covid-19 variant which originated in Brazil and has spread to over 25 countries is about twice as transmissible as some other strains and is more likely to evade the natural immunity that people typically develop from a previous infection, according to a news international. to study.

The research, conducted by a British-Brazilian team of researchers from institutions such as Oxford University, Imperial College London, University of São Paulo, found that the P.1 variant was between 1, 4 and 2.2 times more transmissible than the other variants circulating in Brazil.

It was also “able to escape 25 to 61% of the protective immunity caused by a previous infection” with any previous variant, the researchers found, a sign that current vaccines may also be less effective against it.

International concern about the P.1 variant has intensified recently, with more than 25 countries detecting the variant, including Belgium, Sweden and the United Kingdom, which has identified six cases.

Scientists are expected to publish an article describing the research on Tuesday. Lead author Dr Nuno Faria did not immediately respond to a request for comment. The study has not yet been peer reviewed.

Researchers dated the emergence of the P.1 variant to November 6, 2020, about a month before cases began to increase for the second time in the Brazilian city of Manaus. They found that the proportion of P.1 cases in Manaus rose from zero to 87% within 7 weeks.

The article concludes: “Our results further show that the decline in natural immunity alone is unlikely to explain the dynamics observed in Manaus, with support for P.1 possessing altered epidemiological characteristics.”

“Studies to assess the actual effectiveness of vaccines in response to P.1 are urgently needed,” he added.

The researchers also found that infections were 10 to 80% more likely to result in death in Manaus after the emergence of P.1. However, the authors warned that it was not possible to determine if this meant the variant was more deadly or if it was the result of increased pressure on the city’s health system, or a combination of the two. .

The P.1 variant has more than 17 mutations, which alter its genetic sequence of the virus initially identified in Wuhan, including 3 key changes in the spike protein it uses to enter human cells.

Brazilian researchers used genetic sequencing technology developed by Oxford Nanopore in the UK to identify and track the variant. The technology was first used in Brazil during the Zika outbreak in 2015.

Dr Leila Luheshi, director of applied and clinical markets at Oxford Nanopore, told the Financial Times that while UK variant B.1.1.7 has similar high transmissibility properties to P.1 – it is believed that it’s about 1.5 times more transmissible as the variants that came before it – there was no evidence to date that it has escaped past natural immunity in the same way. Studies to date have also shown that current vaccines retain their efficacy against B.1.1.7.

Luheshi said the problem with P.1 is that “because it has these mutations around the tip. . . the assumption is that the vaccine will be less effective. But she added that there is not yet definitive evidence to support this theory.

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