2023-01-25 16:16:01

Discover XBB again! Will it trigger a new wave of infection? Expert response

Original title: XBB found again! Will it trigger a new wave of infection? Expert response

Discover XBB again! Will it trigger a new wave of infection? Expert response

According to the news on January 3 on the WeChat official account of "Healthy Hangzhou", according to the monitoring of virus strains, the COVID-19 strains detected in local cases in Hangzhou in the past week were Omikron variants BA. 5.2 and BF. 7, of which BA. 5.2 accounted for 54.17% and BF. 7 accounted for 45.83%. At the same time, XBB, BQ. 1, BQ. 1.19 and other Omikjon evolution virus strains were also detected among the inbound personnel under closed-loop management.

Earlier, at the press conference of the joint prevention and control mechanism of the State Council on December 20, Xu Wenbo, director of the Institute of Viral Diseases of the China Center for Disease Control and Prevention, said that China had detected the introduction of BF. 7, BQ. 1 and XBB into China in the past three months, and detected the sub-branch of XBB in 11 cases in three provinces.

In addition, according to the surging news, of the 25 XBB families monitored in Shanghai recently, 3 XBB. 1.5 cases were also imported from abroad, which did not cause local transmission.

XBB.1.5 may become the main strain in the world

Wang Xinyu, deputy director of the Department of Infectious Diseases, Huashan Hospital affiliated to Fudan University and the National Research Center for Infectious Diseases, said that XBB was a sub-variant of Omikjon, which was first discovered in India in August 2022, and was first named by scientists in September. It is believed to be the "recombination" of two different Omikjon variants BA.2.10.1 and BA.2.75 that appeared earlier in 2021.

XBB has further evolved into XBB. 1 and XBB. 1.5. The latter is a rapidly rising variant in some European and American countries, and has occupied a leading position in some countries. However, it seems that its symptoms are not more serious than other variants.

It is reported that experts at home and abroad predict that XBB. 1.5 will become the main strain of the world in a short time, which needs close attention.

Discover XBB again! Will it trigger a new wave of infection? Expert response

On January 1, 2023, Shanghai Nanjing Road Commercial Pedestrian Street ↑

"XBB mainly attacks the gut" is not tenable

According to the Global Initiative for Sharing Influenza Data (GISAID), as of December 31, 2022, XBB.1.5 has been found in at least 74 countries and regions, and has spread to 43 states in the United States. Symptoms of infection with XBB subtype virus include dyspnea, headache, sore throat, nasal congestion, general pain, fatigue and fever.

Is it true that the new strain XBB circulating in the society recently mainly attacks the intestines and causes diarrhea?

Wang Xinyu said that some of the COVID-19 infected people do have digestive tract symptoms, including vomiting and diarrhea. Diarrhoea is not too rare in the symptoms outside the respiratory tract. According to foreign reports, XBB may also cause diarrhea, but there are no more common or serious signs. XBB still mainly invades the respiratory tract, so "XBB mainly attacks the intestinal tract" is not true.

With regard to the rumor that the new strain XBB will attack the human brain, Wang Xinyu said that encephalitis is one of the rare complications of COVID-19 infection, and the symptoms caused are relatively serious. But the probability of occurrence is very low, so we need not be too nervous.

As for "brain fog disease", it is just a "joke" that people tend to forget things or work inefficiently after being infected with COVID-19. It is not a specific medical diagnosis, and it is generally not regarded as a sequela of COVID-19.

XBB.1.5 may not trigger the second wave of infection peak in China

If XBB.1.5 spreads in China, will it trigger a new wave of infection?

"Whether a mutant strain can defeat the existing strain depends on whether its transmissibility occupies a more obvious advantage." Tong Yigang, a virology expert and dean of the School of Life Science and Technology of Beijing University of Chemical Technology, said that XBB.1.5 will have a period of competition with BF. 7 (or BA. 5.2) after entering China, but the new strain with transmission advantages in the United States will not have the same effect in our Congress, and the result is uncertain.

"The generation of the second wave of infection peak depends on two aspects, one is the similarity between the new virus strain and the epidemic virus strain, and the other is the level of the current population immunity." Tong Yigang explained that, on the one hand, although XBB.1.5 is a new subtype and has a mutation of key sites, the neutralizing antibody in the human body is not only targeted at one site of the virus, and there are a large number of neutralizing antibody epitopes (sites) on the surface of the virus, Other sites may also be blocked by antibody neutralization, resulting in the inability of the virus to infect human cells. Therefore, a large number of neutralizing antibodies produced by the epidemic virus strains in the human body still have a certain neutralization effect on the new virus strains, which can also be said to be cross-immune protection. On the other hand, in the newly formed peak of infection in China, many people's immunity through infection is at a high level. Due to the role of cross-immune protection, it is unlikely to be re-infected in the near future.

The results of a large cohort study by the United States Department of Veterans Service and other departments showed that the median interval between the first infection and the second infection was 191 days. The median time between the second infection and the third infection was 158 days. This data is basically consistent with the statement that neutralizing antibodies exist for 6 months.

Previous research by Zhang Wenhong, director of the Department of Infectious Diseases of Huashan Hospital affiliated to Fudan University, also showed that the antibody in the infected person after vaccination can also have a very strong neutralizing effect on other mutants. Zhang Wenhong believes that mixed immunization can build immune barriers against various new mutants.

How to deal with the possible secondary infection caused by XBB and BQ.1?

Hangzhou Municipal Health and Health Commission said that although XBB and BQ.1 may cause secondary infection to people with low immunity, the general public should not worry too much, and should continue to do effective personal protection and social etiquette (one meter of noodles, wash hands frequently, wear masks, more ventilation, etc.), maintain healthy and civilized living habits, and actively vaccinate.