Recently, there have been rumors that the number of severe cases and deaths of the new coronavirus infection has increased because the new coronavirus strains that are prevalent in northern my country are not only Omicron, but also "old strains" such as Delta and even the original strain.

　　Some people judged that the lung infection was caused by the "old strain" based on "Omicron does not invade the lungs"; there are also rumors that the new crown virus is lurking in our country without mutation, and even misquotes the Chinese Center for Disease Control and Prevention's findings According to the data of more than 130 kinds of variation branches, the Omicron branch is said to be Delta.

　　Is it possible that the "old strain" of the new crown has returned?

In response to the above rumors, a reporter from Science and Technology Daily interviewed relevant experts online and concluded three truths.

Truth 1: Severely ill people are being monitored, and no "old strains" have been found

　　"Through whole-genome sequencing, my country has never interrupted the monitoring of domestic epidemic strains." Tong Yigang, a virology expert and dean of the School of Life Science and Technology of Beijing University of Chemical Technology, told reporters that whole-genome sequencing technology can detect more than 30,000 new coronaviruses. Each base is sequenced one by one, and bioinformatics analysis is carried out according to the sequencing results, and then the different mutant strains are classified into the corresponding subtypes.

　　"The novel coronavirus strains infected by critically ill people are actually the focus of our monitoring." Tong Yigang said that monitoring "focuses" on severe illness, and if severe illness is caused by "old strain" infection, it will be monitored immediately.

It has not been monitored so far, which means that it is not a severe disease caused by an "old strain".

　　In order to grasp the dynamics of some highly pathogenic epidemic strains in the first place, most disease control departments will sample and sequence the strains that cause severe diseases.

According to the currently implemented "my country Population Novel Coronavirus Variant Monitoring Work Plan", each province selects three cities, and each city selects a sentinel hospital. Each sentinel hospital collects 15 outpatient and emergency cases and 10 severe cases every week. Genome sequencing and analysis will be performed on samples from all dead cases, and the sequencing data will be uploaded to the China Centers for Disease Control and Prevention within a week.

　　"Not only in Beijing, but in the whole country, no Delta strain or original strain has been found." Tong Yigang consulted the relevant database. He told reporters that thousands of sequencing data monitored by the Chinese Center for Disease Control and Prevention in recent times showed that there was no Delta strain. strains and original strains.

Xu Wenbo, director of the Institute of Viral Diseases of the Chinese Center for Disease Control and Prevention, also said that my country has monitored the introduction of BF.7, BQ.1, and XBB into my country in the past three months, and a total of more than 130 subbranches of Omicron have been imported into my country.

It can be seen that although there are many sub-branches, they are all mutant strains of Aumicron, and no other "old strains" have been found.

Fact 2: Omicron may also cause serious illness

　　"At present, no research has 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 Omicron The pathogenicity of Rong was weaker than that of the previous epidemic strains.

But people still feel that the situation caused by Omicron infection is much more serious than expected, and why?

　　Tong Yigang believes that the main reason is that our country has a large population base. Even if the severe disease rate and mortality rate are very low, the absolute number is still large.

　　On the other hand, people receive a large amount of local information from WeChat and other communication media in a short period of time, and will mistake the local situation for the overall situation, and then there is a part of exaggeration in perception.

　　In addition, some people's deviations in understanding some severe symptoms have also caused exaggeration.

Jiao Yahui, director of the Department of Medical Affairs of the National Health and Health Commission, corrected people's misunderstanding of "white lung": "white lung" is a relatively serious manifestation of pneumonia, and the area of ​​​​the white image area will reach 70%-80%, and the proportion of such patients is very low.

It is not called "white lung" if there is inflammation in the lungs.

Truth 3: In the competition of virus mutant strains, the one with the advantage of spreading wins

　　So, is it possible that the original strain was not cleared and happened to go undetected?

Or is Omicron changing back to a more virulent strain?

　　"The mutation of the virus has no direction. During the replication process of the virus, a mismatch of the genetic code occurs randomly, which leads to the mutation." Tong Yigang said, but whether this mutation can be preserved depends on whether it can bring the virus a new level of immunity. Spread the advantage, and this advantage is the direction of evolution.

Tong Yigang further explained, just imagine, 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 the strongest infection ability will definitely replace the other.

This is like playing Go, the white side (Omicron) can move 10 pieces at a time, and the black side (Delta or original strain) can move 1 piece at a time, and it will not take long for only white pieces to be left on the board.

　　The evolution of the new coronavirus brought about by the transmission advantage has been confirmed many times around the world.

The new coronavirus has gone from the original strain to the Alpha strain to the Delta strain, and then Omicron became the mainstream strain, and there have been continuous iterations between sub-branches, all because the virus strains have the advantages of rapid transmission and immune escape.

　　An expert in the field of bioinformatics data quoted relevant data and said: "From the statistics, the Delta strain has basically disappeared worldwide since late March." (Science and Technology Daily reporter Zhang Jiaxing)