Before the fall of 2019, the coronavirus had spread slowly in Asia and Europe

◎ Science and Technology Daily reporter Lu Chengkuan

What's New! In the early days, the new crown virus spread independently in Asia and Europe.

Researchers from Sun Yat-sen University, the Kunming Institute of Zoology of the Chinese Academy of Sciences, the National Center for Bioinformatics and the University of Chicago found that although the new coronavirus strain in Asia first attracted public health attention, the new crown virus had slowly spread in Asia and Europe before the fall of 2019. As a result of the covid-19 competition between the two places, by April 2020, the Asian strain has been completely replaced by the European strain. The relevant research results were recently published in the National Science Review.

Image source: Visual China

Regarding the origin of the virus and the spread of the epidemic, it is necessary to distinguish between the two different concepts of "the place of origin of the virus" and the "place of outbreak". The origin of any organism, whether it is a person, a dog or angiosperms, often has a long evolutionary process, and biometrics will be formed step by step in this process.

The place of origin of the virus should be a sparsely populated, animal host habitat, where the virus can engage in an "arms race" with its animal host. Subsequently, the virus evolves and matures before spreading to unimmunized populations. The outbreak site is precisely different from the place of origin of the virus, because the population in the outbreak site is not immune to this virus, indicating that the population has not been exposed to the virus in advance.

In short, the place of origin of the virus must have certain conditions for the virus to gradually spread from animals to humans in a long process. So far, there is still no clear scientific evidence and definitive conclusions about the origin of the new crown virus.

From the perspective of population health, the really important issue is not the origin of the virus, but the spread of the epidemic. The virus began to spread after leaving the place of origin, and although the first area of the outbreak was initially the most high-profile, the first place to officially report the outbreak, it is likely that the virus invaded several different places from the place of origin, triggering the outbreak.

In the past, research has focused on virus analysis on strain by strain. Because of the sheer number of strains, there are millions of sequences, and it's easy to overlook the initial changes. The study focused on the study of mutation sites. The total number of mutation sites is less than a hundred, so it is easy to grasp the evolution of the virus in the early, middle and late stages.

The researchers found that the evolution of the virus was replaced by waves of "mutant swarms." From the beginning of 2020 to the end of 2021, there will be at least 5 waves of "mutation groups" in the NEW CROWN outbreak. Each wave is triggered by a strain with a new population of mutations.

The first wave of the "D614G mutation cluster" in early 2020 was very special and was the focus of this study. The 4 mutations of this mutation group (referred to as the DG group mutation) not only did not disappear after the population spread, but became the cornerstone of the entire epidemic.

What's more, when the outbreak first began in early 2020, DG group mutations were already the main strain in Europe and were detected in Italy in September 2019. Before March 2020, DG group mutations were not found in China and are rare in Asia.

As a result, the coronavirus spread independently in Asia and Europe in the early days. Mutations in the DG group appeared in Europe and spread across the globe. Since then, four new strains have spread, including the most recent Delta variant, all of which have evolved from the DG group mutation strains. In the course of the epidemic evolution of the new crown virus, the replacement of mutated strains has occurred many times, and there is a possibility of new replacement in the future.

Source: Science and Technology Daily

Editor: Wang Yu

Review: Julie

Final Judge: Liu Haiying