The new strain XBB has the strongest known ability to escape, and the risk of secondary infection may be increased

According to the latest data from the US Centers for Disease Control and Prevention, a new subtype of Omicron, XBB.
1.
5, has gained a foothold in the United States
.
Currently, about 40% of new confirmed COVID-19 cases in the United States are caused by XBB.
1.
5 infection, up from 20%
a week ago.
In the northeastern United States, even 75% of new confirmed cases are caused by XBB.
1.
5
.

XBB.
1.
5 is a recombination of
the Omicron BA.
2.
10.
1 and BA.
2.
75 subtypes.
Dr.
Barbara Mahon, director of the CDC's Division of Coronavirus and Other Respiratory Viruses, said there is no indication that XBB.
1.
5 is more pathogenic than other Omicron subtypes, and while overall COVID-related hospitalizations are rising across the U.
S.
, the Northeastern United States, which has a higher proportion of XBB.
1.
5 infections, has not seen a proportional increase
in hospitalizations.

On December 13, 2022, the team of He Da Yi of Columbia University in the United States published a research paper
entitled: Alarming antibody evasion properties of rising SARS-CoV-2 BQ and XBB subvariants in the journal Cell.

The study confirmed that the Omicron subtypes BQ.
1, BQ.
1.
1, XBB and XBB.
1 have the strongest known ability to escape neutralizing antibodies, so they may dominate the population because of their superiority in escape neutralizing antibodies and become the new dominant epidemic strain
.

Core mutation sites of BQ and XBB

This study showed that the neutralization ability of the new crown vaccine and infected people to BQ.
1, BQ.
1.
1, XBB and XBB.
1 was significantly reduced, including the serum
of WA1/BA.
5 bivalent mRNA vaccine-reinforced individuals.

Neutralizing antibody titers against BQ and XBB were reduced by 13-81-fold and 66-155-fold, respectively, which far exceeded any previously observed COVID mutant strains
.
Monoclonal antibodies that can neutralize early Omicron are basically ineffective
against these Omicron subtypes.

Overall, the findings suggest that BQ and XBB pose a serious threat to current COVID vaccines, including bivalent mRNA vaccines against mutant strains, and that all current therapeutic monoclonal antibodies are ineffective
against them.
Therefore, BQ and XBB may dominate the population because of their dominance in escape-neutralizing antibodies and become the new dominant epidemic strains
.

On December 6, 2022, Peiyong Shi et al.
of the University of Texas Medical Department published a research paper in Nature Medcine entitled Low neutralization of SARS-CoV-2 Omicron BA.
2.
75.
2, BQ.
1.
1, and XBB.
1 by parental mRNA vaccine or a BA.
5-bivalent booster
。

The study showed that the bivalent mRNA vaccine against Omicron BA.
4/5 did not have a strong neutralizing effect
on the new Omicron subtypes BA.
2.
75.
2, BQ.
1.
1, or XBB.
1.
Previous infection with the new coronavirus significantly increases the level of
neutralizing antibodies produced by bivalent mRNA vaccines.

According to CNBC, Johns Hopkins University virologist Andrew Pekosz said in an interview with CNBC that XBB.
1.
5 has additional mutations compared to XBB, allowing it to attach better to cells, which may lead to its ability to infect humans
more effectively.

The World Health Organization (WHO) said XBB has been detected in at least 70 countries around the world and began to cause a surge
in infections in parts of Asia (India and Singapore, among others) in October.
Studies conducted in the lab have found that XBB is able to evade antibodies produced by previous coronavirus infections or vaccinations, which means that XBBs may be more likely to cause infection or reinfection
.
This has been confirmed
in clinical cases and hospitalizations.

In general, XBB and XBB.
1.
5 are Omicron subtypes, like BA.
5.
2 and BF.
7 currently popular in China, and their pathogenicity is not significantly different, but XBB and XBB.
1.
5 are more transmissible and immune evasion ability is the strongest
known.

At present, XBB and XBB.
1.
5 have been introduced into China, but they have not yet formed a dominant spread
.
Recent domestic infections are mainly due to BF.
7 (mainly northern) and BA.
5.
2 (mainly southern), and for immunocompetent people who have recently been infected with BF.
7 and BA.
5.
2, these Omicron subtypes, the possibility of reinfection with XBB or XBB.
1.
5 in the short term is small
.