The domestic epidemic is still not fully controlled. The concentrated epidemics in many places and the spread of epidemics have affected the normal life and work of many friends. From the current domestic and international epidemic situation Look, the Omicron variant has replaced other variants and has become the absolutely dominant strain causing the current global pandemic. According to documents released by the WHO, the proportion of newly infected Omicron has already accounted for More than 90% of the total number of infected people.
The reason why this variant strain can become the dominant strain for transmission is the result of gradual selection in the process of immune pressure and natural differentiation. From the current relevant research results, Omicron is more transmissible, but is asymptomatic after infection, and has more mild cases, resulting in a lower chance of severe hospitalization than other variants.
As there are many mild and asymptomatic infections caused by Omikron infection, many people are still calling for further liberalization and choosing the strategy of “lying flat” to face the new crown virus, but is it actually advisable to do so? The epidemic has been going on for more than two years. Under the epidemic, due to the implementation of various prevention and control policies, it has indeed affected many aspects of work and life of many friends. Many friends are tired of the current epidemic prevention and control. Therefore, it is completely understandable to hope that the epidemic will end soon and life will return to normal. But judging from the current situation and the characteristics of the main epidemic strain Omicron itself, choosing to “lie down” to coexist with the virus is definitely not a good choice for us.
Whether they can let go and lie down, in fact, countries such as the United Kingdom and the United States, which have been in the midst of a pandemic, have long given hints. After they chose to let go, they would have The epidemic was not well controlled, and the peak of the pandemic further appeared. Although relevant studies have found that the virulence of the Omicron strain has indeed weakened compared with the Delta strain, due to its super-transmissibility, infection has been caused. The number of people is also larger, so the challenges and pressures it brings to the public health system are also great.
At the recent press conference on joint prevention and control of the State Council, experts from China CDC further pointed out that the harm caused by Omicron is far higher. to the flu. Judging from the data of the outbreak in Hong Kong, more than 1.1 million people have been infected, and more than 8,000 deaths have been reported. The mortality rate (0.7%) is much higher than the fatality rate of influenza.
The fatality rate is higher than that of influenza, and the transmission power is many times stronger than that of influenza. The outbreak of a wide-ranging virus infection, although the proportion of severe hospitalizations has decreased, the pressure on the medical system must be unbearable for us. Further rise, which is what we do not want to see.
Many friends don’t understand: It is also the new coronavirus, why is the Omicron variant so powerful? A new study recently published in the international medical journal “Nature” revealed the possible reasons for this, and Omicron does have certain uniqueness compared to other variants, from the type of mutation to the affinity for infecting human tissues, And the way it enters the cell may be quite different from other variants of the new coronavirus.
In this study, the researchers compared the SARS-CoV-2 wild-type virus, D614G, Alhpa variant, Beta variant, Delta variant and Omicron variant. Replication ability and cell tropism, through the degree of binding of variants in human bronchiolar and lung in vitro cultures, the results show that the reason why Omicron has super transmissibility is related to some of the cell-binding properties of the virus itself. close relationship.
The researchers assessed the replication rate of each variant after infection by tissue culture infectious dose titration. When comparing the wild virus strain, the delta variant, and the Omicron variant, the experimental It was found that the delta variant and the omocron variant replicated significantly more in human bronchi than the wild strain, and the omocron virus had significantly higher titers when replicating at 24 and 48 hpi. This difference More than 70 times! In the in vitro culture of human lung tissue, the replication of Omicron was reduced compared with that of the wild strain.
In addition, the researchers also performed immunohistological staining studies on virus-infected isolated tissues, which also showed that Omicron binds to bronchial cells. The ability is stronger, and the infection intensity of replication in the lungs is reduced.
in vitro culture of human respiratory tract Tissue tropism of SARS-CoV-2 variants.
This also proves from the basis of tissue biology why the Ormicron strain is less virulent than other variants such as Delta, There is also a lower risk of hospitalization due to symptoms. An epidemiological study from South Africa and an epidemiological study from the United Kingdom showed that, the probability of severe hospitalization due to infection with the Omicron strain decreased by about 25% compared with the delta strain.
In the discussion section of the article, the researchers pointed out that the results of this study show that compared with the wild strain and the delta variant, Omicron has a Significantly higher replication capacity, and this property of more rapid replication in the bronchi, results in a higher viral load in the body’s upper respiratory tract and a further increase in the amount of infectious virus released when breathing and speaking , thereby enhancing the spread of the virus in the air. In a related report, it was also found that, unlike the delta variant, Omicron also showed strong replication ability in cultures of human nasal epithelial cells differentiated in vitro, a condition that also causes the patient’s exhaled air. Small particle aerosols containing the virus will further increase.
The researchers pointed out that the ACE2 enzyme is more widely expressed in human bronchi than in the lung, and Omicron is different from other variant viruses in that The structural variation of Omicron itself leads to a higher degree of binding to the ACE2 enzyme, and in terms of the process of invading cells, the researchers speculate that Omicron mainly stimulates the cell membrane of the body to produce invaginated vesicles. It is combined with cells by endocytosis, while other new coronavirus variants are generally combined by direct fusion with cells, and this endocytosis pathway can broaden the cell spectrum of virus infection and enable Omic Rong also infects more types of cells in the human body with ACE2 expression.
This also reveals the risk of the Ormicron strain from the biological mechanism, which has super transmission characteristics. The reason why it causes less severe disease is that it has It is caused by the weak ability of transmission and replication in the human body, but due to its unique binding method with human cells and the increase in the degree of binding with the ACE2 enzyme, after Omicron infects the human body, the range of infected tissues and organs may be larger than that of the human body. Other variants have higher risks, and for the possible sequelae of infection with Omicron, because the time for Omicron to cause a pandemic is still short, follow-up related research is needed to really understand.
Therefore, in front of Omicron, choosing a reasonable method and performing dynamic reset is a better way to control the epidemic. It will bring huge risks to the country, and it seems that it cannot be relaxed at present.
Pharmacist Li’s original article on health, please do not reprint without authorization, offenders will be prosecuted!