No new Covid-19 variants have been detected in China after the country saw a surge in infections following the end of its zero-Covid policy in December 2022. Cases in the capital of Beijing were analysed but no mutations of the virus were identified.
The study, published in The Lancet, suggests that two existing Omicron sub-variants (BA.5.2 and BF.7, among the most dominant variants in Beijing in 2022) accounted for more than 90% of local infections between 14 November and 20 December 2022.
"Given the impact that variants have had on the course of the pandemic, it was important to investigate whether any new ones emerged following the recent changes to China’s Covid-19 prevention and control policies," said Lead author Professor George Gao of the Institute of Microbiology at the Chinese Academy of Sciences.
A snapshot of the pandemic
"Our analysis suggests two known Omicron sub-variants – rather than any new variants – have chiefly been responsible for the current surge in Beijing, and likely China as a whole," Gao said. But as the virus continues to circulate widely, the epidemiological situation will continue to be monitored, "so that any new variants that might emerge are found as early as possible."
The results represent "a snapshot of the pandemic in China," due to the characteristics of Beijing’s population and the circulation of highly transmissible Covid-19 strains there, the authors said.
Since China lifted its strict Covid-19 control policies in early December (and its travel ban a month later) at a time when its cases were surging, experts and authorities across the world voiced concern and called for the situation to be monitored closely. In the three years since Covid-19 was declared a global pandemic, the emergence of variants such as Alpha, Beta, Gamma, Delta, and Omicron caused multiple waves of cases around the world.
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In this latest study, genome sequences from samples detected in Beijing were generated using rapid, large-scale sequencing technology. Their evolutionary history and population dynamics were analysed using existing high-quality Covid-19 sequences. From a total of 2,881 high-quality sequences, 413 new samples were randomly selected and analysis revealed that they all belonged to existing, known Covid-19 strains.
"It is welcome to see this much-needed data from China and reassuring that this study yielded no evidence for novel variants. But this is no surprise: the surge is largely explained by the abrupt cessation of effective control measures," said Professor Wolfgang Preiser and Dr Tongai Maponga of the South African University of Stellenbosch, which was not involved in the study.
Nonetheless, experts urged caution in drawing conclusions about China as a whole based only on data from Beijing. "The SARS-CoV-2 molecular epidemiological profile in one region of a vast and densely populated country cannot be extrapolated to the entire country. Other evolutionary dynamics might unfold in other regions, possibly including animal species that could become infected by human beings and 'spill back' a further evolved virus."
