WEDNESDAY, Feb. 8, 2023 (HealthDay News) -- Amidst the recent COVID-19 outbreak in China, scientists are saying it appears no new variants developed.

“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 George Gao, of the Institute of Microbiology at the Chinese Academy of Sciences in Beijing.

“Our analysis suggests two known Omicron subvariants -- rather than any new variants -- have chiefly been responsible for the current surge in Beijing, and likely China as a whole," Gao said in a news release from The Lancet. The study was published in the journal Feb. 9.

However, he added, since COVID-19 is still widely circulating in China, it is important to monitor the situation closely so that any new variants that might emerge are found as early as possible.

Researchers did a genome analysis of 413 new COVID-19 infections in Beijing during the time period when China lifted its strictest pandemic control policies.

More than 90% of local infections in Beijing between Nov. 14 and Dec. 20, 2022 involved Omicron subvariants BA.5.2 or BF.7, according to the study. Imported cases mostly involved different variants from those dominant in Beijing.

It has been widely reported that China ended its zero-COVID strategy on Dec. 7, which had included targeted lockdowns, mass testing and quarantine. Cases surged after that, raising speculation that new variants might have emerged.

For the study, researchers sampled 2,881 genome sequences, randomly selecting 413 of them. About 350 were local cases and 63 were imported from 63 countries and regions.

The dominant strain in Beijing after Nov. 14 was BF.7, which accounted for nearly 76% of local infections. BA5.2 was found in about 16% of local cases.

Although the data was collected only in Beijing, rather than the Chinese mainland, the authors said the data is representative of the country as a whole.

However, the true number of cases may be underestimated because large-scale testing ended. Also, more sampling is needed to study transmissibility of Omicron subvariants.

“It is welcome to see this much-needed data from China. It is certainly reassuring that this study yielded no evidence for novel variants but not a surprise: The surge is amply explained by the abrupt cessation of effective control measure,” said virologists Wolfgang Preiser and Dr. Tongai Maponga of the University of Stellenbosch, South Africa, in a commentary published with the study.

However, Preiser and Maponga urged caution in drawing conclusions about China as a whole based 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. In other regions of China, other evolutionary dynamics might unfold, possibly including animal species that could become infected by human beings and 'spill back' a further evolved virus," Preiser and Maponga said.

More information

The World Health Organization has more on tracking COVID-19 variants.

SOURCE: The Lancet, news release, Feb. 8, 2023