On November 14, Zhang Boli, an academician of the Chinese Academy of Engineering, told a reporter from Science and Technology Daily: "The data of infected people in recent days shows that most of the current confirmed infections are asymptomatic infections . This infection is the result of the selection of the new coronavirus under the premise that the herd immunity barrier in my country is basically formed (the full vaccination rate of vaccine in the entire population exceeds 90%, and the full vaccination rate of basic immunization over 60 years old exceeds 85%). "This evolution is beneficial for a specific branch of the new coronavirus to maintain an 'advantage'. Therefore, speculates from the evolutionary law of viruses that the probability of the new coronavirus becoming stable and its virulence weakening is relatively high. "
What is the evolutionary law of viruses? Will it really become weaker and weaker as it evolves? In the context of the new coronavirus spreading around the world, in order to occupy the limited survival resource of human beings, different strains have started a survival inclination game called "evolution". In this cruel game, only strains with the following characteristics can stand out.
have mild symptoms and are easy to identify. Elimination. Under natural conditions, people with severe symptoms will choose to rest in bed, and their activities will naturally decrease, so the virus will lose many opportunities for transmission. The more extreme is Ebola virus , because the symptoms after infection are too severe and serious, and the infected people will quickly become bedridden or even die, so they have not been able to spread to places outside Africa. In the prevention and control of new crown , due to body temperature measurement, self-symptom monitoring and . The existence of in the fever clinic, infected people with severe symptoms are easily identified and isolated, and the spread of the virus cannot be achieved. In fact, it is precisely humans' high-intensity monitoring and control of the new coronavirus that has accelerated the evolution of the virus towards asymptomatic and mild symptoms.
has a fast pass-through speed and a slow elimination. If other conditions are equal, the faster the virus reproduction, the more offspring it can produce, thus winning in the competition. The average incubation period of the new coronavirus has been shortened from 5 days of the original strain to about 3 days of Omickron . With the same transmission time, the number of infected people produced by Omickron may be more than ten times that of the original strain, but it is beneficial to prevention and control that infected people can detect positive faster, and the time for close contacts to needs to be isolated and observed has also been shortened. The viruses reproduced by
are easy to The victory of the excretion is eliminated, and the unrestricted cannot be eliminated. After the new generation of viruses are produced, it needs to be excreted from the body to infect the next person. For respiratory viruses, the most ideal place to detoxify is undoubtedly the upper respiratory tract, and viruses with strong binding ability to the lungs will have a considerable number of viruses locked in the lungs, resulting in inefficient transmission. Combined with the lungs, the ability to cause pneumonia is obviously unfavorable to the spread of the virus, so the proportion of infected people with symptoms of pneumonia is getting lower and lower.
is easy to bind to host cells, and those with low binding ability are eliminated. 's current new coronavirus has a very high ability to bind human cells, and few virus particles can be transmitted. Therefore, when passing by such low-risk exposure can also be transmitted.
has strong immune escape ability, and those with low escape ability are eliminated. people are infected with the original virus or are vaccinated. After that, immunity will be generated, and the original strain will not be easily infected again, forcing the new coronavirus to quickly replace parts and update themselves. The differences between the overall characteristics and the original strain will become increasingly greater.
Let’s take a look at the inversion process of the new coronavirus from a global dimension (see the figure below). From early 2020 to October, people around the world have not been infected with the new coronavirus, so the original strain spreads smoothly and has few mutations. 2020 At the end of the year, the Alpha strain, which is more contagious and has also had a high pathogenicity, appeared, and occupied an advantageous position in almost half a year. However, in March 2021, the Alpha strain had not yet dominated the world, and the Delta strain, which spread faster and had milder symptoms, emerged, almost forcing other strains to a dead end within half a year. It was also in 2021 that the proportion of asymptomatic infections of the new crown increased significantly, and reports of deaths of infected people in China were very rare.In 2022, the Omickron strain appeared, and its infectious ability surpassed almost all infectious diseases recorded in human history. The arrogant Delta strain was removed in just three months. So far, the new coronavirus strain detected worldwide has 100% of the offspring of the Omickron strain. At the same time, Omickron's pathogenicity continued to decline, and upper respiratory tract symptoms became the main clinical feature. Reports of severe illness and death generally only appear in people with high age or with underlying diseases.
Data source: https://gisaid.org/hcov19-variants/
Viral mutation continues to exist. Will a strain with a strong pathogenicity be mutated in the future? In theory, certainly! But according to the laws of evolution, this strain will soon be squeezed into survival by its relatively gentle siblings who focus on spreading and reproduction, and will be quickly eliminated in the involuntary movement of this virus, which will not cause a few splashes.
