The highly transmissible variant emerged with a host of unusual mutations. Now scientists are trying to work out how it evolved.
produced by people who have been vaccinated, or who have been infected with earlier variants.
Although researchers have submitted almost 7.5 million SARS-CoV-2 sequences to the GISAID genome database, hundreds of millions of viral genomes from people with COVID-19 worldwide have not been sequenced. South Africa, with some 28,000 genomes, has sequenced less than 1% of its known COVID-19 cases, and many nearby countries, from Tanzania to Zimbabwe and Mozambique, have submitted fewer than 1,000 sequences to GISAID .
“This is not the nineteenth century, where you take six months to go from point to point by sailboat,” says Sergei Pond, a computational evolutionary biologist at Temple University in Philadelphia, Pennsylvania. Such chronic infections have been observed in people with compromised immune systems who cannot easily get rid of SARS-CoV-2. For example, a December 2020 case report described a 45-year-old man with a persistent infection. During almost five months in its host, SARS-CoV-2 accumulated close to a dozen amino-acid changes in its spike protein.
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