Brazilian Covid variant may infect people who have recovered from virus

A woman is tested for coronavirus in Manaus, where a virus outbreak has been driven by the new variant

Credit: Edmar Barros/AP

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The Brazilian coronavirus variant may infect people who have already recovered from Covid, scientists said as they called for urgent investigations into whether the new mutation can escape previous immunity.

Britain is preparing to ban travel to Brazil over concerns about importing the new variant. The move follows a huge rise in cases in Manaus, a city that had been believed to be close to herd immunity from the first wave.

Research published last year suggested that 76 per cent of people in Manaus had contracted coronavirus by October, which should have severely limited onward spread of the virus. However, the city saw an unexpected surge of new cases last month and has now declared a state of emergency, with hospitals reaching 100 per cent capacity. 

A new study by an international team of researchers, including scientists at Imperial College and Edinburgh University, found that 41 per cent of cases in Manaus are now caused by the new variant. It has mutated to be more infectious and carries changes that help it evade the immune system.

Genetic sequencing has shown that at least one person who caught the virus in the first wave has been infected with the new variant. Scientists warned there had been a "rapid increase" in cases in locations where previous infection rates were thought to have been very high.

They said it was essential to investigate "whether there is an increased risk of re-infection in previously exposed individuals".

Professor Sharon Peacock, director of the Covid-19 Genomics UK Consortium (COG-UK), said the Brazilian variant was worrying because it shared mutation N501 with the UK variant, which is believed to have increased transmissibility between 50 and 77 per cent. It also had other mutations that stopped antibodies from working.

"The fact the virus has the N501 means we know that it’s likely to be more transmissible, so that already rings alarm bells – and if it’s then carrying other mutations which could have other properties, we clearly need to take it seriously," she said. "But we have the tools to detect this and the public health capabilities to prevent spread."

On Wednesday, Boris Johnson said he was "concerned" about the Brazilian variant, which has already spread to Japan but could be wider because many countries do not have sequencing surveillance programmes to look for mutations. 

The UK variant, which was detected in September, has already spread to 35 countries, and the South African variant was found in Britain in December.

Felipe Naveca, the deputy director of research at major research centre Fiocruz Amazonía, based in Manaus, warned recently that the variant is likely to become widespread.

"If these mutations confer any selective advantage for viral transmissibility, we should expect an increase in the frequency of these viral lineages in Brazil and in the world in the coming months," he said.

Ravi Gupta, professor of microbiology at the University of Cambridge, said: "The Brazilian variant has three key mutations in the spike receptor binding domain [RBD] that largely mirror some of the mutations we are worried about in the South African variant, hence the concern.  

"The SARS-CoV-2 RBD is one of the main targets for our immune defences and also the region targeted by vaccines and changes within this region are therefore worrisome."