Are more changes possible in the future for new crown strains? How will it evolve? CDC experts explain

December 20, 2022December 20, 2022

Read Time:1 Minute, 48 Second

In the afternoon of Dec. 20, the State Council held a press conference on the theme of “Introduction of Medical Services for Key Populations”. Experts in the fields of immunization planning, virology, respiratory and infectious diseases, and child health attended the conference and answered questions from the media.

A reporter asked, “The new coronavirus has been mutating, but at present it is still mainly the Omicron subbranch, may the new coronavirus change more in the future? What is the trend of its evolution? Will there be strains that are highly infectious and lethal?

Xu Wenbo, director of the Institute of Viral Diseases of the CDC, said that since the emergence of Omicron in November 2021, as of December 18, 2022, it has evolved from 5 branches, BA1 to BA5, to 709 subbranches, of which 72 are recombinant viruses, and SBB is one of the 72 species. The mutation of the Omicron strain continues as long as it circulates in the population, it will replicate, and the replication will lead to genomic mutation, and there are two forms of mutation, one is the mutation of the virus itself leading to mutation of the antigenic site, resulting in immune escape. The trend of mutation is from the earliest early strains, initially Alpha dominant, then Delta, then BA1 instead of Delta, then BA2 instead of BA1, and finally BA5 instead of BA2. The domestic strains of Omicron series are very sensitive, so BA5.2 is dominant. The whole trend of mutation is based on immune escape, which will cause an increase in population transmission, which is the trend of mutation.

Secondly, will it have increased transmission and lethality in the future? This possibility is relatively small. There are now 709 subbranches of Omicron, and the cases of hospitalization, serious illness and death are significantly lower than those of the earlier Delta strain and other VOC mutants. 700 branches have not seen an increase in serious illness and death, so it is less likely that the future mutation trend will become significantly more pathogenic overall. Overall, it is less likely to produce strains that are both highly infectious and have increased pathogenicity.