A new strain of the virus has arrived? It has been found in more than 60 countries around the world! Will it come to our home?

If you ask what everyone is most worried about recently, it is nothing more than reinfection after Yang Kang. After all, the "eight tortures" of the new crown are not something that everyone can endure. Recently, the current round of the domestic epidemic is coming to an end, and the number of outpatient (emergency) visits, the number of critically ill patients in the hospital, and the number of deaths in the hospital have all shown a downward trend. On the other hand, various versions and sub-variants of the Omicron variant are constantly causing new infection peaks, among which CH.1.1, known as the "two-headed dog", has attracted much attention .

It is reported that as of January 30, 2023, CH.1.1 has been detected in 67 countries or regions, mainly in the United Kingdom, Denmark, Singapore and other countries. So, what are the characteristics of CH.1.1? Will it become a dominant strain? Will it have a greater impact on us? This article explains them one by one.

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01

What are the characteristics of CH.1.1?

How did the two-headed dog get its name?

From the sub-lineage of the Omicron variant, CH.1.1 belongs to the sixth-generation sub-branch of the Omicron variant BA.2.75, which was first collected and discovered in India in July 2022. After the sub-variant was discovered, some experts named it "Orthrus", which means "two-headed dog", a monster in Greek mythology with a snake tail. Although it sounds scary, just like the previous Omicron variant BQ1.1 was called "Hellhound", it is just a code name and has no direct connection with the virus itself.

However, compared with many previous variants, CH.1.1 does have some points worthy of attention. According to the known mutation patterns of the new coronavirus, newly emerged variants that have caused a certain impact will be enhanced in infectivity and immune escape, and the same is true for CH.1.1. Studies have found that it can bind well to the ACE2 receptor. This receptor is the receptor that mediates the entry of the new coronavirus into host cells and is widely distributed on respiratory mucosa and cardiovascular endothelial cells. This means that CH.1.1 may be more contagious and more likely to break through, at least partially, the antibody immunity formed by the human body after previous infection and/or vaccination, increasing the risk of breakthrough infection.

It is worth noting that the new subvariant CH.1.1 not only has multiple new mutation sites, but also one of them is L452R mutation. The mutation of this site was previously considered to be unique to the Delta variant. As research continues to deepen, it is found that this mutation also exists in other variants of Mysterious Kron, such as BA.5.3 and BA.5.1.3. The impact of the mutation at this site is still unknown, but because the toxicity of the Delta variant is generally strong, it is necessary to pay further attention.

02

What will be the future global impact of the two-headed dog?

Is it a flash in the pan, or will it become the dominant strain?

There is no increase in toxicity, but there is still the possibility of causing a wider impact. The virus has been around for nearly half a year and has been found in 67 countries or regions. According to data from the past month, CH.1.1 and its subbranches account for more than 6% of the global sequence number, especially in the United Kingdom, Denmark, Singapore and other countries, where new epidemic trends have been caused. Monitoring data in the United States shows that the proportion ranks fifth and has a continuous upward trend. This also means that the scope of influence of CH.1.1 is gradually expanding, and there is a possibility of further escalation.

On the other hand, although the subvariant contains the L452R mutation, its toxicity has not been observed to increase. However, a domestic authoritative organization also stated that when a new strain appears, the number of infected cases must reach a certain scale and last for a period of time before a preliminary judgment can be made as to whether the pathogenicity of the new strain has changed.

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03

Will CH.1.1 have a greater impact on us?

After implementing the "Class B Management", China is still monitoring the dynamics of the spread of the Omicron series of novel coronavirus variants in China and the proportion of its various subtypes in real time. So far, 24 cases of CH.1.1 and its subclades have been found, all of which are imported cases.

After experiencing the peak of the epidemic caused by BA.5.2 and BF.7 as the main epidemic strains, this round of epidemic has entered a low epidemic period. At the social level, more than 80% of residents have been infected with the new coronavirus, and the immune barrier is at a relatively high level. Affected by cross-protection factors, the risk of large-scale infection in the short term is low. Nevertheless, due to the stronger infectivity and immune escape of CH.1.1, the risk of breakthrough infection still exists. Especially for the elderly, those with serious underlying diseases and poor immunity, the risk of reinfection is relatively high.

The impact of the new variant on the world is still there, and we must not let down our guard. The WHO Emergency Committee held a routine quarterly assessment meeting on the COVID-19 pandemic on January 27, announcing that the COVID-19 pandemic still constitutes an "international public health emergency" and that the global COVID-19 emergency is still in place. WHO experts believe that according to the relevant standards of the International Health Regulations, COVID-19 infection is still a dangerous infectious disease that has the ability to cause significant damage to health and health systems. Moreover, vaccine coverage in low- and middle-income countries and high-risk groups around the world is still insufficient, and there is still uncertainty as to whether new variants of the virus will emerge. Therefore, long-term public health actions are still urgently needed to eliminate the impact of the epidemic.

The impact of the novel coronavirus on humans may continue to exist for a certain period of time, and monitoring of new variants is of great significance. For us, it is not only necessary to understand the relevant knowledge, but also to pay attention to whether self-protection measures are in place. Regardless of the variant, cutting off the transmission route is one of the best means of prevention.

Author: Zhang Yu, researcher at the Chinese Center for Disease Control and Prevention, doctor of medicine, and master's supervisor

Review | Gu Li, Director of the Department of Infection and Clinical Microbiology, Beijing Chaoyang Hospital, Capital Medical University; Tao Ning, Institute of Biophysics, Chinese Academy of Sciences

This article is produced by the "Science Rumor Refutation Platform" (ID: Science_Facts). Please indicate the source when reprinting.

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