Introduction
At the end of the National Day holiday, what we worry about will follow - The epidemic broke out again in many places .
Recently, the new coronavirus Omickron lineage variant has accelerated its epidemic around the world, including the newly launched BA.2.75, BA.4.6, BF.7 and other mutant strains, which have attracted widespread attention from WHO . The latest mutant strain BQ.1.1 has also entered the public eye due to the particularity of its mutation sites.
On September 28, the first confirmed case of BF.7 was found in Hohhot, Inner Mongolia Autonomous Region, my country. Six days later, the number of confirmed cases reached more than 500, and so far the number of confirmed cases has exceeded 1,200.
WHO issued a statement saying that BF.7 may set off a new pandemic and we need to pay attention to it. Recently, the magazine " Nature " also published an article mentioning that there may be new strains of the epidemic this fall and winter. Will the world fall into a new wave of epidemic this autumn and winter?
Li Xiaowei | Written by
On September 28, Hohhot, Inner Mongolia Autonomous Region, my country, reported a local case of new coronary pneumonia infection. After genetic sequencing, it belongs to the Omickron BF.7 variant strain. This is the first time that BF.7 has caused a local epidemic in China.
As of October 8, the Inner Mongolia Autonomous Region has a total of 1,225 confirmed cases. Where did the
BF.7 strain come from? Will it become a new generation of "king"?
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BF.7 strain comes from?
Just as the world enters autumn and winter, the new mutant strains of the Omickron lineage have not stopped "evolution" and have produced one new mutant strain after another.
BF.7 first appeared in Belgium on May 13, and was named BF.7 on July 16 (BF.7 is a branch of BA.5). BF.7 now accounts for 25% of the new cases in Belgium. in Germany, France and Denmark, the proportion of cases of this variant reaches 10%.
Recently, the proportion of BF.7 cases in the United States has also increased rapidly within two weeks, surpassing other mutants. According to data from the Centers for Disease Control and Prevention (CDC), on October 8, the proportion of BF.7 cases in the United States reached 4.6%, while the infection rate of BA.5 decreased slightly, but it was still the mainstream strain (79.2%).
The prevalence of each strain released by the US CDC
BF.7 strain epidemic trend chart (green)
BA.5 has been the mainstream strain in the United States recently, but it has gradually become a stable downward trend. At the same time, BA.4.6 and BF.7 gradually began to increase, and BF.7 grew rapidly. The first time CDC followed this variant was last week, with the proportion at 1.7% at that time, the proportion at the second week was 2.6%, and the current proportion at 4.6%. According to this growth trend, BF.7 does have the potential to become a new generation of "king". The emerging strain of
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is not the only one aspect of the growth trend of the virus. What we are more concerned about is the toxicity and escape ability of the new strain.
is currently running on the frontline of the popular trends at the same time as the BF.7 variant strain, and there are many emerging variant strains of the Omickron lineage. We use a picture to understand the large family of variant strains since BA.2.
Omickron BA.2 and its variants. The figure is derived from Marc Johnson
The figure above clearly describes the origin and important mutation sites of the various variants of the Omickron family since BA.2. Among them, BF.7 is mutated from BA.5.2, and the mutation site is R346T.
It is worth mentioning that the mutation sites of BA.4.6 and BE.1.2, which are in the same frame as BF.7, are also R346T, which is in line with a concept commonly mentioned in the scientific community - " convergence evolution ".
In this figure, Professor Marc Johnson, a molecular virologist at the University of Missouri, made a hypothesis that the five sites of spike proteins 346, 444, 452, 460 and 486 are the sites where the virus can adapt to the environment and have the most significant virulence gain. BF.7 only has three of the mutation sites - R346, L452, and F486. It is obvious that the most dangerous strain in this picture has become BQ.1.1 (with the above five mutation sites).
To explore such a huge mutant family system, Professor at Peking University Xie Xiaoliang and Cao Yunlong published a preprint article on bioRxiv entitled "Imprinted SARS-CoV-2 humoral immunity induces convergent Omicron RBD evolution". The article was launched on October 4, 2022.
In this paper, Xie Xiaoliang analyzed the growth advantages of existing emerging variants, confirmed several new variants with more immune escape, and further confirmed the characteristics of the virus being "convergent evolution".
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BF.7 has growth advantages and is more escaped than BA.5
Omickron BA.1, BA.2 and BA.5 show strong neutralizing antibody escape ability, posing a serious challenge to people's immune barriers established through vaccination and infection.
However, the scale of the Omickron "family" is still expanding. Importantly, a large portion of these emerging variants showed significant growth advantages over BA.5, such as BA.2.3.20, BA.2.75.2, CA.1, BR.2, BN.1, BM.1.1.1, BU.1, BQ.1.1 and XBB.
Convergence evolution diagram of Omickron variants with growth advantages compared to BA.5 Figure is derived from the paper
It is worth noting that although these derivative mutations appear to diverge during evolution, the mutations they carry on the receptor binding domain (RBD) converge to the same sites, including R346, K444, V445, G446, N450, L452, N460, F486, F490 and R493, in line with the “convergence evolution” we mentioned above.
studies have shown that the above-mentioned "convergence mutations" will cause the virus to significantly escape neutralizing antibodies in the serum, including serum of recovered patients from BA.5 breakthrough infection. It was further found that the above mutations could also allow the virus to escape existing antibody drugs, including Evusheld and Bebtelovimab.
Specifically, BR.2, CA.1, BQ.1.1, BM.1.1.1 strains, especially XBB, are the strains with the strongest escape ability of the antibody in the test, far exceeding BA.5 and close to the level of the original strain of new crown .
c-f, i.e. pseudovirus neutralization titer
, the data above shows that the antibodies in the body of the subjects who received were poorly effective against the XBB strain after three injections of Sinovac and those infected with BA.1, BA.2 or BA.5 after vaccination.
This also shows that the current herd immunity and BA.5 vaccine enhancement injection may not provide people with sufficient widespread infection protection. Xie Xiaoliang's team pointed out that the development of broad-spectrum COVID-19 vaccines and NAb drugs should become the top priority, and the constructed convergent mutants can be used to check their effectiveness in advance.
Back to the initial question, will we usher in a new wave of the new crown epidemic this autumn and winter?
This news from Nature magazine explores the factors that may drive the wave of the new crown epidemic and what countries can do to mitigate the impact of Omickron. researchers point out that emerging variants may bring about new waves of infection in the fall and winter.
infectious disease epidemiologist Justin Lessler said that the launch of bivalent vaccines against the original coronavirus and Omickron is "a bit slow" and all current signs indicate that Omickron is evolving and producing a new generation of immune escape variants.
"" As we enter the fall and winter, this may lead to a rise in cases in some countries ," Leatherer added.
Epidemiology , Brown University, Providence, Rhode Island, pointed out that some states in the United States have begun to see a rise in cases.
To sum up, the mutation of the new coronavirus is far from over, and the "evolution" of the strain is still in progress. The development of broad-spectrum vaccines and broad-spectrum drugs is no longer in a hurry.
References
1.Will there be a COVID winter wave? What scientists say (nature.com)
2.Iprinted SARS-CoV-2 humoral immunity induces convergent Omicron RBD evolution | bioRxiv
3.Tracking SARS-CoV-2 variants (who.int)
4.COVID Data Tracker Weekly Review | CDC
5.CDC COVID Data Tracker: Variant Proportions
6.New Covid variant BF.7 spreading quickly and could be dominant 'within weeks' - Daily Record
