HONG KONG — Analysis of Covid-19 cases in Beijing suggests no new variants have emerged from the recent outbreak in China, according to a study published Wednesday.

Faced with rare mass riots after nearly three years of strict «covid zero» policies, the Chinese government lifted most restrictions on December 7. The sudden change unleashed the coronavirus over the winter on a population of 1.4 billion people who had barely been exposed to it, raising fears the outbreak could produce a new strain of concern and prompting dozens of countries, including the United States, to impose tests and other restrictions on travelers from China.

But China-funded study, which was published in The Lancet, found that of 413 infections sampled in Beijing, all belonged to existing covid variants. The most common were the omicron subvariants BA.5.2 and BF.7, which together accounted for more than 90% of local infections.

Samples were randomly selected for genomic sequencing from a larger pool of 2,881 high-quality samples collected in Beijing from November 14 to December 20, 2022.

George Gao, lead author of the study and a professor at the Institute of Microbiology of the Chinese Academy of Sciences, said it was important to investigate whether new variants emerged during the China outbreak given the impact others like delta and omicron have had on the course of the pandemic.

«Our analysis suggests that two known omicron sub-variants, rather than new variants, have been primarily responsible for the current increase in Beijing, and likely China as a whole,» said Gao, former director of the China Center for Disease Control and Prevention. Diseases. in a press release.

«However, with the continuing large-scale circulation of Covid-19 in China, it is important that we continue to monitor the situation closely so that any new variants that may emerge are found as soon as possible.»

Although the study covered a short period early in the outbreak and sampling was limited to Beijing, its findings are in line with reports from Italy and other countries that have been testing China’s arrival for covid and sequencing the results, Tongai said. Maponga, a researcher in the Division of Medical Virology at the University of Stellenbosch in South Africa.

“Whatever they are detecting in travelers originating from China is the same thing that we already know is circulating elsewhere,” said Maponga, who was not involved in the Beijing study.

The study was also limited by the fact that China ended large-scale mandatory testing in December, making it difficult to know the total number of cases in the outbreak, and therefore what percentage of total cases the tests represent. samples.

After being held in check for most of the pandemic, the virus appears to have swept through China much faster than many other countries, beginning to pick up speed last fall even before Covid restrictions were lifted. Beijing and other major cities experienced some of the first outbreaks.

Zeng Guang, a former chief epidemiologist at the Chinese CDC, said in late December that more than 80% of Beijing residents had likely contracted the virus. A study published in January by researchers at the University of Hong Kong said it could be over 92% by January 31.

People wearing face masks cross an intersection in Beijing, Tuesday, February 7, 2023.
People wearing masks in Beijing on Tuesday.Mark Schiefelbein/AP

Chinese authorities say a feared surge during the Lunar New Year holiday period, when hundreds of millions of people travel to their hometowns to visit family and that began in mid-January, has not materialized. But the outbreak has still been a major source of anxiety for Chinese people who had been taught to fear Covid-19 and devastating for those who have lost loved ones to the disease.

Global fears that a new variant could emerge were compounded by what the World Health Organization and others said was a lack of data from China on its outbreak. China defended its data and criticized the travel measures as unscientific and discriminatory.

Chinese authorities have released more data in recent weeks, saying hospitals have recorded around 80,000 covid-related deaths since early December. Many experts say the true number is much higher, with British forecaster Airfinity estimating 608,000 deaths between December 1 and January 17.

The Chinese CDC most recently reported 3,278 Covid-related deaths nationwide from January 27 to February 2, about half the number from the previous week. It says daily covid infections peaked at 6.94 million on December 22 and have since fallen to about 24,000 as of January 30.

Maponga noted that a new variant of concern could yet emerge anywhere in the world, underscoring the need for continued testing, genomic surveillance and transparent data sharing.

«While It continues to circulate, infecting both people and animals, the virus will always be developing mutations because that is the nature of viruses,» he said.