Lack of social distancing has exploded cases of the new Manaus strain in Brazil

At the end of 2020, researchers detected the P.1 variant for the first time in people who had returned to Japan from Manaus., the capital of the Brazilian state of Amazonas.

Over the weeks, infections caused by the variant multiplied exponentially and overwhelmed Manaus, which had already experienced one of the highest documented rates of SARS-CoV-2 infection in the world during its first wave. Since the emergence of P.1, Scientists have found evidence that it is more transmissible than some other variants and more easily escapes antibodies.

“What we saw was an even harder meltdown than what we had experienced before, like something out of a horror movie. It’s hard to describe what happened in Manaus,” said Dr Felipe Gomes Naveca, a virologist who co-led the study of Drug the Nature, and who works at the city’s Leônidas and Maria Deane research center, which is part of the Oswaldo Cruz Foundation (Fiocruz) in Rio de Janeiro.

To plot the magnification of P.1, a team led by Gomes Naveca and Gonzalo Bello, virologist at the Oswaldo Cruz Institute in Rio de Janeiro, another part of the Fiocruz foundation, sequenced the genomes of 250 SARS-CoV-2 samples collected across the Amazon between March 2020 and January 2021, and performed more limited genetic testing for P.1 on hundreds of other samples.

The team’s analysis revealed that the prevalence of P.1 was increasing impressively in Amazonas, the variant that quickly replaced other bloodlines in circulation. There was no sign of the variant in 355 samples as of November 2020, but it made up almost three-quarters of the samples by mid-January 2021.

When the mitigation measures were relaxed and the social distancing index fell below 40%, in September 2020, the durable variant of SARS-COV-2 (B.1.1.28) in Brazil fell. extent, and the other (B.1.195) died out, thus completing the process of replacement of the lineage. Thus, the lower social distancing observed in the municipalities of the interior of the state of Amazonas from Manaus was the likely driver of the first lineage replacement and its transmissibility was significantly reduced in mid-April when the distancing social welfare in Manaus increased by 50%.

According to the researchers, the increase in P.1 coincided with the end of the first wave, the slackening of the population with regard to care measures, mainly, the reduction of social distancing in Manaus and the rest of Amazonas. It could have been related to the Christmas and New Years holidays, as well as in the municipal elections in November. The researchers believe that these potential super-spread events, combined with the variant’s higher transmissibility, helped P.1 to thrive.

A study of blood donors in Manaus found that The first wave of SARS-CoV-2 infected 76% of the city’s population last October, suggesting herd immunity had already been achieved.

Assuming re-infection is rare and immunity to infection was not significantly reduced last December, a second wave of COVID-19 would not be expected so soon. Several hypotheses have been put forward to explain this unexpected second wave that led to the collapse of the health system in Manaus between the end of the year and 2021. “Our results confirm that non-pharmaceutical interventions (INF) could explain much of the dynamics of the epidemic in Amazonas,” says lead author Felipe Naveca.

Evidence indicates that the first epidemic wave in the Amazon was relatively controlled by the implementation of NPI, before collective immunity. Our results also confirm that the NPIs were not strict enough to systematically reduce the reproductive rate of Amazonian lineages or SARS-CoV-2 variants. and that, on the other hand, a stationary state of endemic community transmission was maintained from May to September last ”.

In another study, published as a pre-post on the virological.org discussion board last month, the same team found that variants carrying many of the same disturbing mutations as P.1 circulated in the Amazon for months without catalyzing. a second wave. . This finding has not yet been peer reviewed. Genomic analysis links a devastating second wave of COVID in Brazil and an increase in travel and contact.

Bello suspects that these “P.1-like” variants are also highly transmissible, but that it was periods of lax social distancing that caused P.1 to explode. “You need these mutations combined with epidemiological factors, then you have the perfect storm.”

Tulio de Oliveira, bioinformatician and director of the KwaZulu-Natal Research Innovation and Sequencing Platform in Durban, South Africa, says The research shows how teams from southern countries can conduct cutting-edge research in genomic epidemiology. Tackling the pandemic, he notes, is helping local networks thrive. “What we want to see in these documents in the future is that they can do this much faster.”

In summary, experts note that the variant of the coronavirus behind the fierce second wave of COVID-19 in Brazil emerged, in part, due to lax social distancing, according to an analysis of viral sequences from the epicenter of the epidemic.

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