No new COVID-19 variants emerged in China’s recent surge of infections when the country ended its zero-COVID policy, according to an analysis published in The Lancet.

Genome analysis of 413 new infections in Beijing since the strict pandemic controls were lifted suggests they were all caused by existing threads, The Lancet said.

“More than 90% of local infections in Beijing between November 14 and December 20, 2022, involved Omicron sub-variants BA.5.2 or BF.7,” The Lancet said. “Imported cases during the same period mostly involved different variants to those dominant in Beijing.”

China reportedly ended its zero-COVID strategies in December. Those included targeted lockdowns, mass testing, and quarantines. Case numbers have surged, raising concerns that new variants might emerge, The Lancet said.

Variants such as Alpha, Beta, Gamma, Delta, and Omicron have caused waves of cases around the world since the pandemic began. Observers have worried about new strains emerging in China since the policy change.

The study’s authors analyzed local and imported cases in Beijing since December 2019 and said there were no persistent local transmissions reported in Beijing before last December.

“The results could be considered a snapshot of China, due to the frequent population exchange and the presence of circulating strains with high transmissibility,” the study said.

In the current study, they looked at COVID-19 samples from Beijing last year. “Genome sequences were generated using rapid, large-scale sequencing technology, and their evolutionary history and population dynamics analysed using existing high quality COVID-19 sequences,” The Lancet said in a press release.

More than 400 samples were analyzed, and all were found to belong to existing strains. The dominant strain in Beijing after November 14, 2022, was BF.7. It accounted for 75.7% of local infections, BA5.2 accounted for 16.3%.

Source

The Lancet: “Characterisation of SARS-CoV-2 variants in Beijing during 2022: an epidemiological and phylogenetic analysis”

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