The Foreign dominant Strains of Omicron in China

Will foreign dominant strains trigger a new round of epidemics in China?

"BQ.1 and XBB are new Omicron variant branches, and they have become dominant strains in some European and American countries." At the press conference of the Joint Prevention and Control Mechanism of the State Council on December 20, According to Xu Wenbo, director of the Chinese Center for Disease Control and Prevention, in the past three months, my country has monitored more than 130 sub-branches of Omicron, including BQ.1 and XBB.

The new dominant strain has been introduced into our country, will it trigger a new round of epidemic? Can people who have already been infected with the new coronavirus be reinfected?

The prevalence of new mutant strains can be monitored in real time

According to reports, after the optimization of the new crown epidemic prevention and control strategy, the Institute of Viral Diseases of the Chinese Center for Disease Control and Prevention formulated the "Working Plan for Surveillance of New Coronavirus Mutant Strains in my country's Population" based on the reality that multiple new coronavirus subtypes circulate in my country. The plan requires each province to select 3 cities, each city to select a sentinel hospital, and each sentinel hospital collects samples from 15 outpatient and emergency cases, 10 severe cases and all death cases for genome sequencing and analysis every week, and Within a week, the sequencing data will be uploaded to the national novel coronavirus genome database established by the China Center for Disease Control and Prevention.

Xu Wenbo introduced that through the above-mentioned scheme, it is possible to dynamically monitor the prevalence of the new coronavirus Omicron series variants in China and the proportion of each subtype in real time, and new variants with potential changes in biological characteristics, including clinical manifestations, transmission. It can provide scientific basis for the development of vaccines and the evaluation of diagnostic reagents (including nucleic acids and antigens, etc.).

The new strain has not yet formed a dominant spread in China

Due to the increased transmissibility and immune escape ability of BQ.1 and XBB, it gradually transformed into the dominant strain in other countries. So, how do they perform in our country?

Current monitoring results show that more than 130 subclades of Omicron, including BQ.1 and XBB, have been imported into my country. Of these, 50 subclades caused associated indigenous cases or outbreaks. BQ.1 and its subclade have been detected in 49 cases in 9 provinces, and XBB subclade has been detected in 11 cases in 3 provinces.

"BQ.1 and XBB have not yet formed a dominant spread in my country." Xu Wenbo introduced that the viruses currently spreading in my country are still dominated by BA.5.2 and BF.7.

"However, its propagation advantages will gradually increase." Xu Wenbo said that monitoring analysis believes that BQ.1, XBB, BA.5.2, BF.7 and more than 50 other sub-branches may form a co-circulation.

"In the countries where BQ.1 and XBB are prevalent, there is no significant increase in the rate of severe disease and mortality." Xu Wenbo said that at present, it seems that the new mainstream variant strain is no different from other series of variant strains of Omicron in terms of its virulence.

From the perspective of preventing BQ.1 and XBB, Xu Wenbo believes that, like the prevention of other Omicron variants, everyone should be the first person responsible for their own health.

In order to monitor whether the pathogenicity of the new strain has changed, research institutions will combine the genomic variation and clinical characteristics of the new strain. Xu Wenbo said that if there are any changes in the clinical characteristics of the virus after infection, it will be linked to the genomic characteristics for research and judgment, but there are no reports of BQ.1 and XBB causing severe cases and deaths at home and abroad.

Time interval can trigger reinfection

"Now we are infected with BF.7 and BA.5.2. If new mutant strains appear, there is still a risk of re-infection." Wang Guiqiang, An Infectious Diseases expert at Peking University First Hospital, said frankly that after the infection recovered, he would be infected with the new coronavirus again after a period of time , often due to the mutation of the new coronavirus.

Wang Guiqiang introduced the possibility of reinfection and the interval between reinfection. He said that from the current data, the risk of reinfection with the Omicron strain is higher than that of the previous Delta and original strains. Generally, there will be a period of interval before the secondary infection occurs, and it will not be reinfected soon after infection.

"The time interval of breakthrough reinfection is closely related to clinical manifestations." Wang Guiqiang said that the shorter the interval, the lighter the symptoms, and the longer the interval, the more serious the symptoms are, which is directly related to immunity.

A study in Sweden found that secondary infections or three infections with different strains of Omicron had milder symptoms, and they were basically asymptomatic infections or mild cases.

Wang Guiqiang also emphasized that the elderly should avoid reinfection. Studies have shown that if the elderly are reinfected, some patients will suffer from severe illness or even die. Therefore, it is necessary to fully realize that vaccination can reduce the occurrence and severity of secondary infections, and it is again recommended that the elderly and those with underlying diseases be vaccinated as soon as possible.