China News Agency, Beijing, January 4th. The China Centers for Disease Control and Prevention posted on its official social media account on January 4th that a total of 16 local XBB cases were reported from October to December 2022, all of which were XBB.1 evolutionary branches. Concentrated from October to November, there was only one case in December, and no local cases of XBB.1.5 have been detected yet. The possibility of large-scale epidemics caused by XBB series variants in China in the short term is extremely low.

  According to reports, XBB is a recombinant strain of two mutant strains BJ.1 and BM.1.1.1 derived from the new coronavirus Omicron BA.2.

As the sub-branches of the XBB series become increasingly popular in the United States and other countries, the sub-branch derived from XBB, XBB.1.5, has further enhanced its spreading advantage compared with other sub-branches of XBB.

  The article stated that since November, the proportion of XBB.1.5 in the number of people infected with the new crown in the United States has gradually increased.

According to the forecast of weekly surveillance cases in the United States, the proportion of XBB.1.5 has reached 40.5% on December 30, 2022, which may replace BQ.1.1 and BQ.1 and become the dominant epidemic strain in the United States.

As of January 2, 2023, XBB.1.5 has been detected in at least 25 countries and regions around the world.

  Regarding the current existence of XBB.1.5 in China, the article pointed out that among the imported cases, from October to December 2022, China has found 199 imported XBB cases through genome sequencing, including 9 subclades, 4 of which are XBB. 1.5 Imported cases.

  Regarding whether XBB.1.5 will cause the second round of infection of the new coronavirus, the article stated that there are reports that XBB.1.5 may have a strong immune escape ability, which has attracted international attention.

However, monitoring data from the U.S. Centers for Disease Control and Prevention confirmed that during the increase in the proportion of XBB series variants in recent weeks, the number of reported cases of new crown infection, the number of hospitalized cases, and the number of deaths did not increase significantly.

In the United States, the reinfection rate caused by XBB.1.5 needs further dynamic observation.

  The article pointed out that BA.5.2 and BF.7 are the absolute dominant strains currently prevalent in China. The neutralizing antibodies produced by individuals after infection with BA.5.2 or BF.7 will remain relatively stable in the short term (3 months). High level, expected to have better cross-protection against other Omicron variant clades (including XBB).

The possibility of a large-scale epidemic caused by XBB series variants including XBB.1.5 in a short period of time (3 months) in China is extremely low.

  Regarding the pathogenicity and virulence of XBB.1.5, the article believes that although XBB.1.5 has attracted worldwide attention, at present, no country has reported an increase in the pathogenicity of XBB.1.5 infected persons, nor has there been any hospitalization rate and There have been reports of an increase in the proportion of cases and deaths, and no differences in the clinical symptoms caused by it and other Aomekronia branches have been seen.

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