The BF.7 or BA.5.2 strains currently circulating in my country appear relatively primitive compared to the globally prevalent strains. Currently, two mutant strains, BQ.1 and XBB, are gradually becoming popular around the world. In some countries and regions, they have become pop

As the Omicron virus continues to mutate, new mutant strains have emerged one after another. The BF.7 or BA.5.2 strains currently circulating in my country appear relatively primitive compared to the globally prevalent strains.

Currently, two mutant strains, BQ.1 and XBB, are gradually becoming popular around the world. In some countries and regions, they have become popular dominant strains. They have also been found in my country, which requires our attention. The source of

BQ.1 and XBB.

Currently, Omicron has 5 subtypes, BA.1, BA.2, BA.3, BA.4, and BA.5, which have evolved into 709 sub-branches, including 72 recombinant variant branches. The

BQ.1 and XBB virus strains are both "submutants" derived from the Omicron variant .

BQ.1 is the sixth-generation subclade of the Omicron BA.5 strain, and BQ.1.1 is the first-generation subclade of BQ.1. It was first discovered in Nigeria in June 2022, became popular in European and American countries in September, and gradually became popular in Japan and Singapore in October.

XBB is a recombinant strain of BA.5 and BA.2. It originated in India and has become popular in Singapore, Thailand, Japan and other Asian countries, and also in the northeastern United States.

During the widespread epidemic, the Omicron variant will continue to generate more sub-branches through genetic variation and recombination between Omicron mutants. The situation of two strains of

in my country.

In the past three months, cases of infection with BQ.1 and XBB strains have been detected in my country.

Currently, more than 130 sub-branches of Omicron have been introduced into my country, including BQ.1 and XBB. BQ.1 and its subclades were detected in 49 cases in 9 provinces, and the XBB subclade was detected in 11 cases in 3 provinces.

The dominant strains currently prevalent in my country are still the BF.7 and BA.5.2 strains. BQ.1 and XBB have not yet formed dominant transmission in our country, but their transmissibility is very alarming. The R0 value of XBB is 25, and the R0 value of BQ.1 is 26. The transmissibility is nearly twice that of BA.5.

Their speed will become faster and faster, and they are likely to become the dominant strain popular in our country.

Basic characteristics of the two strains. Compared with the Omicron BF.7 or BA.5 strains currently popular in my country, the

BQ.1 and XBB strains have no increased pathogenicity, but their transmissibility and immune evasion ability have been significantly enhanced.

Director of the Institute of Viral Diseases of the Chinese Center for Disease Control and Prevention Xu Wenbo said that some European and American countries have gradually shown that the transmissibility and immune evasion ability of its dominant strain have increased, but its pathogenicity has not increased, and the severe disease rate and mortality rate have not increased in these countries where BQ.1 and XBB are prevalent.

Let’s take a look at the situation in Singapore, where XBB has a dominant position. The number of severe cases and deaths in Singapore has been declining, and the ICU occupancy rate is also declining. The overall epidemic situation is showing a downward trend . It can be seen that the pathogenicity of the XBB strain has not increased.

Regarding secondary infection.

Jin Dongyan, a professor at the Li Ka Shing School of Medicine at the University of Hong Kong, believes that overall, the incidence of repeated infections is very low. Theoretically, the probability of a person being infected with one subclade of Omicron and then being infected with another subclade exists, but judging from the current situation, the probability of this event occurring within 3 months and within 3-6 months is very low.

Judging from the data in Hong Kong, the probability of repeated infection among the people is less than 5%. However, among key groups, including those over 60 years old and those under 60 with underlying diseases, the probability of repeated infection is increasing and can reach 30%. This needs our attention.

In fact, whether secondary infection will occur mainly depends on two aspects. First, the similarity between the two strains. The closer the strains are, the smaller the chance of reinfection; the more severe the mutation of the strain, the higher the chance of reinfection. The second is the individual's immune situation. Antibodies will be produced in the body after the initial infection. As time goes by, the immune protection gradually weakens. The longer the time, the higher the chance of secondary infection.

What deserves our more attention is how fast XBB and BQ.1 spread, whether or when they will become the dominant strain in the country, and whether the pathogenic power of the Omicron strain will be significantly enhanced after layers of mutations, etc.