A nurse at Peking Union Medical College Hospital monitors a critically ill patient in the ICU ward at midnight on New Year's Day on January 1, 2023. Photo: Cui Meng/GT

The possibility of a large-scale epidemic in China within a short period of at least three months caused by XBB variants including XBB.1.5 is extremely low, according to an article released by the Chinese Center for Disease Control and Prevention (China's CDC) on Wednesday on its official WeChat account.

The main strains currently circulating in China are BA.5.2 and BF.7. The neutralizing antibodies produced by BA.5.2 or BF7-infected individuals remain at a high level in the short term, and offer better cross-protection against variants including XBB, CDC said.

A new COVID variant known as XBB.1.5 is spreading fast in the US and threatening to cause further waves of infection. It's one of the latest descendants of Omicron, the highly transmissible version of COVID, causing the number of cases in the US more than doubled in a week at the end of December.

The XBB.1.5 variant accounts for about 41 percent of confirmed COVID cases across the country, according to the data published by the US Centers for Disease Control and Prevention on December 30, 2022.

The variant has an unusual mutation that is helping it spread. The mutation changes part of the COVID virus that many antibodies from vaccination or previous infection target, according to the Guardian.

A total of 199 imported cases of XBB variants were detected by genome sequencing in China from October to December, 2022, including nine sub-branches, four of which were imported XBB.1.5 cases. Moreover, a total of 16 domestic cases of XBB have been reported, all of which are evolutionary branches of XBB.1 variant. No domestic case of XBB.1.5 has been detected so far, China's CDC confirmed.

A total of 369 viral sequencing results of the domestic COVID-19 cases in China have been shared by a research team in Shanghai, showing that at least 30 known Omicron subvariants have been detected in the city but no new variant has been identified.

The mutation allows the variant to evade antibodies without compromising how well it attaches to human cells. "The mutation can give that immune evasion without the cost to infectivity," The Guardian quoted Ravi Gupta, professor of clinical microbiology at the University of Cambridge, as saying.

Although the variant may have strong immune evasion, data from the US CDC confirmed that the number of COVID-19 infections reported, hospitalized cases and deaths did not increase significantly in recent weeks when the proportion of XBB variants increased.

"The virulence of XBB.1.5 is no different from other mutant strains of Omicron and the rate of severe illness and mortality rate have not increased significantly in the countries where BQ.1 and XBB are prevalent," Xu Wenbo, director of the Institute of Viral Diseases, China's CDC, said during a press briefing on December 20, 2022.

In addition, China's CDC also noted that there is no evidence that XBB.1.5 causes severe diarrhea or other gastrointestinal clinical manifestations more than other viruses.

The CDC also reminded the public to take precautions against the virus, including regular exercise, maintaining good indoor ventilation, and keeping a healthy diet to improve their immunity.

The elderly and patients with serious underlying diseases should monitor their own health and wear masks in public settings, the CDC said, adding that people who get infected with COVID-19 within three to six months have a very low chance of reinfection.

Global Times