XE spreads better than Omicron BA.2?
Writing | Jun Ling
Source | “Medical Community” Public Account
Recently, a new coronavirus variant with more transmission power than Omicron BA.2, XE, was introduced into China.
According to the Taiwan United News Network on April 2, Luo Yijun, deputy head of the medical response team of the Taiwan Command Center, confirmed that there was one case of the XE mutant strain in Taiwan.
XE is a “combination” of Ormicron variant strains BA.1 and BA.2. It was first detected in the UK on January 19, and thereafter Israel, India, Spain, Brazil, the Czech Republic, and Japan have also found XE infections one after another.
The World Health Organization said that it has an additional 10% transmission advantage over the currently popular Omicron BA.2 variant, which may be the most spreading new coronavirus variant. As of April 5, at least 1,125 cases of XE variant infection have been reported in the UK, where XE was first discovered.
XE spreads better than Omicron BA.2?
In its latest report, the UK Health Safety Authority states:
XE’s growth rate was 12.6% higher than BA.2 through data analysis as of March 30. In the last 3 weeks, the XE growth advantage has reached 20.9%.
In terms of characteristics, XE is more like belonging to the BA.2 lineage, the spike protein is still a feature of BA.2, and the front end of the genome carries a segment of BA.1. Virology expert Chang Rongshan boldly judged to the “medical community” based on its transmission power that the “recombinant strain” of the Omicron family may become one of the new coronavirus epidemic strains within 1 to 2 years.
“The more transmissible mutants have a greater survival advantage, and XE’s transmissibility is about 4 times that of the original strain, but such mutants are less likely than the female parent. When the transmission power of ‘quality’ increases, the virulence will not increase.” Chang Rongshan believes that it is enough to wait and see, but it is not enough to have a substantial impact on the global epidemic prevention situation.
Jin Dongyan, a professor at the School of Biomedical Sciences of the University of Hong Kong and an expert in virology, believes that XE does not pose too many threats. Compared with BA.2, which took over a month to sweep the world, XE appeared. For two months, it has always been “not sullen and not angry”.
“This is related to the mutation characteristics of the virus. Taking XE as an example, its two female parents are BA.1 and BA.2, both of which are of the Omicron pedigree and are highly similar. It’s like ‘consanguineous marriage’, the offspring are unlikely to be very different from the mother parent, and it is also very difficult to defeat the mother parent in terms of transmission.” Jin Dongyan said.
Is Delta Chron a super mutant?
In addition to mutants such as XE, which are formed by “crossing” the Omicron family itself, the recombinant “Delta Chiron” previously produced by the combination of Delta and Omicron , is more of a concern.
On March 8, an article published by French scientists on the preprint platform medRxiv confirmed the existence of the “Delta Chron” variant strain XD. Through genome sequencing, it was found that XD was Delta A hybrid of AY.4 and Omicron BA.1.
As of March 31, XD variants have been detected in France, Denmark, the Netherlands, Belgium and Germany, with 63 gene sequences characteristic of XD variants identified in France.
On the other side of the English Channel, another “Delta Chron”, named XF, was found in the UK. According to the British Health and Safety Agency, as of March 25, 38 cases of XF have been found. Infection cases.
From the name point of view, “Delta Chron” seems to combine the virulence of Delta and the super transmission power of Omicron, but in fact, whether it is XD and XF, There is no evidence that they will pose a new wave of epidemic risk, nor have they been found to produce stronger resistance to existing vaccines.
The alphabet is running out,
How risky are variants?
In addition to XE, XD, XF, the world also reported XG found in Denmark, XJ in Finland, XK in Belgium, XM in Germany…
The World Health Organization says recombination is common in coronaviruses and is a predictable event. Professor Jeremy Kamil of Louisiana State University Shreveport said in an interview:
There is a lot of “hype” about these variants, and while they are scientifically interesting, the truth is that most of them don’t pose a real threat.
To what extent do we need to be alert to threats from new mutants? How should you react? Several virology experts also published their analysis and insights.
Medicine
How should the public view the recurring Covid-19 variants objectively?
Jin Dongyan:
Viral mutations are common, and don’t panic just by looking at laboratory studies and various “reports,” but focus on real-world data. If a variant strain has a transmission advantage, for example, in a certain area, more than 30% of the infection is caused by it, then it means that a problem may arise.
It is enough to stay on the sidelines and be vigilant in the short term. Most of the new variants have no advantage in the epidemic, and from the overall trend of the pandemic so far, the new coronavirus has not become stronger.
Chang Rongshan:
In a sense, the virus mutation is not too scary for most young people, and the threat of virulence is very small.
The main concern centers on the “medical run” and the resulting “secondary disaster”, especially among the elderly. Although the infection mortality rate of the new coronavirus has dropped significantly, the rapidly increasing transmission power will lead to the shortage of medical resources, which may lead to an increase in the absolute number of deaths that are negatively related to the pathogenicity of the epidemic strains.
Medicine
Will there be future “super mutants” with enhanced transmission and virulence?
Jin Dongyan:
Subsequent strains may appear that are more transmissible than Omicron, but their pathogenicity will not increase. This is related to the mutation characteristics of the virus. The increase in toxicity caused by mutation is an “accident” in itself, and it is difficult to sustain.
In order for the virus to become the dominant strain and continue to spread, it must adapt to the human body and coexist with the host for a long time, which will inevitably lead to the weakening of pathogenicity. If the pathogenicity is very strong and the host is “killed”, it is not conducive to the reproduction of the virus.
Chang Rongshan:
At present, the mutation trend of the new coronavirus has generally taken shape, that is, the ability of transmission and immune escape has gradually increased, but the increase will not be very large. Omicron’s transmission power has approached the “ceiling” and has gained great adaptability in the crowd.
Reduced pathogenicity is also a relatively reliable mutation direction. In the future, the pathogenicity may continue to be reduced to the level of common cold, but I estimate that it will take 10 years or more. .
Mengji Lu, a Chinese-German virologist and professor at the Institute of Virology, University of Essen, Faculty of Medicine:
The genome of RNA viruses is prone to accumulation of mutations, and it is normal to have various mutants.
Some scholars believe that delta-like mutant strains may return again, and it is not ruled out that they will show stronger toxicity. Based on this concern, Germany advocates that people who recover from infection should also participate in vaccination to improve immunity.
Globally infected and vaccinated populations have great differences in immunity. The threat of the same variant to different groups of people is also different. We need more real-world data to evaluate their impact on a country, and we cannot generalize.
Medicine
In what circumstances would a new dominant variant emerge?
Chang Rongshan:
A large number of infected people gather, and repeated transmission and infection of the virus may lead to the emergence of new mutant strains, but the survival advantage of new mutant strains generated in this case generally will not have a “qualitative” leap .
The main threat is the cross-species spread of the virus. Infecting enough new “intermediate hosts” that the virus evolves in animals and then passes back to humans may produce new “strong” mutants. On this basis, if multiple species can be infected at the same time, and cross-species frequently occurs among these species, the related threat will be further improved.
“For example, Omicron.” Chang Rongshan quoted the team of Academician Xu Jianguo of the Chinese Center for Disease Control and the team of Professor Sun Yamin of the Institute of Public Health and Health of Nankai University in the authoritative professional journal “Biosafety and Biotechnology”. A research paper in the Journal of Security, which suggests that Omicron did not evolve from Delta, but may have originated in mice, evolved and evolved in the mouse host and then passed back to humans.
The average cross-species frequency of SARS-like coronaviruses is once a thousand years, and the new coronavirus has been found in about 10 species within 2 years, which may indicate that the cross-species frequency of the new coronavirus is Thousands of times more than similar viruses, suggesting that we need to strengthen research on the cross-species transmission of the new coronavirus.
Medicine
In terms of epidemic prevention strategies, how should we deal with the mutation of the new coronavirus?
Jin Dongyan:
We need to develop better, more targeted vaccines. From the perspective of Omicron, the existing nucleic acid tests and antigen tests can be effectively found, and the vaccine can also effectively protect severe illness and death.
Chang Rongshan:
The evolutionary trend of the new coronavirus suggests that physical prevention and control can do more and more limited, “cost-effective” is getting lower and lower, no matter how fast the early detection will be missed. In the long run, in large cities with high population density, the extension of the new crown infection chain to the elderly cannot be completely eliminated.
Therefore, it is imperative to increase the vaccination rate of the elderly, and at the same time promote the further development and optimization of vaccines and new crown specific drugs. Young people are relatively safe.
Lu Mengji:
The constant mutation of the virus will make some neutralizing antibodies ineffective. Therefore, in addition to increasing the antibody titer through booster vaccination, the key is that the vaccine must be able to stimulate T cell immunity and prevent severe disease. From this point of view, the mRNA vaccine has the relatively best efficacy among all the vaccines of the current technical route.
In the end, with the continuous emergence of new coronavirus variants, the “infection resistance” that relies on antibodies will eventually fail. After the population has acquired basic immunity through vaccination or infection, the pathogenicity of the variant strain will be reduced to a very low level, and like other various respiratory infections, it will have a limited impact on our health.
At present, the biggest problem in the world is how to protect high-risk groups. After widespread vaccination, it is foreseeable that each of us must exert our own immunity through repeated contact with the virus. power to overcome the threat of virus infection. Because the virus canThey are also a permanent threat to high-risk and vulnerable populations by continuing to spread through the population through mutations. High-risk and vulnerable populations have low immunity and are vulnerable to mutant strains, and targeted vaccination to strengthen immunity will help.
Source: Medicine
Editor in charge: Zheng Huaju
Proofreading: Zang Hengjia
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