The Joint Prevention and Control Mechanism of the State Council issued the "Overall Plan for Implementing "Category B and B Controls" on New Coronavirus Infections on December 26. The plan points out that at present, experts at home and abroad generally believe that the general direction of the new coronavirus mutation is lower pathogenicity, more inclined to upper respiratory tract infection and a shorter incubation period.
9 Omicron subtype strains are circulating in my country
Xu Wenbo, director of the Institute of Virology of the Chinese Center for Disease Control and Prevention, Xu Wenbo said that currently the BA.5.2 and BF.7 of the Omicron mutant strains are still the overwhelmingly dominant strains circulating in the country. The recent rumors that Delta and Omicron are co-circulating or recombining are false rumors.
Xu Wenbo, Director of the Institute of Viral Diseases of the Chinese Center for Disease Control and Prevention: Recently there are some rumors on the Internet that there are co-circulations or recombination of Delta and Omicron in the north. This is a false rumor because no delta virus recirculation has been found in domestic monitoring.
Omicron From December 1st to 27th, the whole country has completed the whole-genome sequencing of 1,142 cases, indicating that BA5.2 and BF.7 have an absolute advantage in the national prevalence, and their combined total has reached more than 80%; there are other subtypes, A total of 9 subtypes have been detected nationwide, and no characteristic genomic mutations have been found in these subtypes.
At the same time, we also found imported cases this month. From December 1st to 27th, a total of 31 Omicronia branches were found imported into the country, including BA5.2 and BF.7, and among the 31 variants, these two are dominant.
virus mutant strains compete, the one with the transmission advantage wins
So, is it possible that the original virus strain has "uncleared remnants" and happened to not be detected? Or is Omicron turning back into a more virulent strain?
"It is true that the mutation of the virus has no direction. During the virus replication process, mismatches of the genetic code appear randomly, which leads to mutation." Tong Yigang, virology expert and dean of the School of Life Science and Technology, Beijing University of Chemical Technology, said, but whether this mutation can be preserved depends on whether it can bring a transmission advantage to the virus, and this advantage is the direction of evolution.
Tong Yigang further explained that if there are two different strains of Omicron and Delta circulating in the same place at the same time, whoever has the fastest transmission ability and strong infection ability will definitely replace the other. This is like playing Go. White (Omicron) can move 10 pieces each time, and Black (Delta or Original Strain) can move 1 piece each time. Soon there will only be white pieces left on the board.
The evolution of the new coronavirus brought about by its transmission advantages has been confirmed many times around the world. The new coronavirus went from the original strain to the Alpha strain to the Delta strain, and then Omicron became the mainstream strain, and there were continuous iterations between sub-branches, all because the virus strain has the advantages of rapid spread and immune evasion.
An expert in the field of bioinformatics data quoted the global series of monitoring data of new coronavirus strains and told reporters: "From our data statistics, the Delta strain has basically disappeared globally since late March."
Omicron may also cause pneumonia Inflammation
"No study has ever confirmed that Omicron only infects the upper respiratory tract or does not cause severe illness. Even if the influenza virus mainly infects the upper respiratory tract, it can also cause pneumonia in some people." Tong Yigang said that the current clinical situation shows that the pathogenicity of Omicron is weaker than that of previous epidemic strains.
However, people still feel that the situation caused by Omicron infection is much more serious than expected. Why?
Tong Yigang believes that the main reason is that our country has a large population base. Even if the seriousness rate and death rate are very low, the absolute number is still very large.On the other hand, people receive a large amount of local information in a short period of time from media such as , WeChat, , etc., and will mistake the local situation for the overall situation, and then there is some exaggeration in perception.
In addition, there are also deviations in the understanding of some severe symptoms that have also led to exaggeration. Jiao Yahui, Director of the Medical Affairs Department of the National Health Commission, corrected people's misunderstandings about "white lung": White lung is a relatively serious form of pneumonia, and the white image area will reach 70%-80%. The proportion of such patients is very low. It doesn’t mean that inflammation of the lungs is called white lung. Not all the white lungs mentioned on the Internet are real white lungs.
Source: CCTV News, Science and Technology Daily
