Scientists have traced the source of the spread of coronavirus in China

Scientists have traced the source of the spread of coronavirus in China
Scientists have traced the source of the spread of coronavirus in China

The transmission of a new type of coronavirus from person to person began in November or early December last year. This is how the virus got to the seafood market in Wuhan, from where it spread throughout the country. This is the conclusion reached by scientists from a tropical botanical garden at the Chinese Academy of Sciences.

Experts analyzed the genomic data of 93 samples of a new type of coronavirus collected in 12 countries on four continents (which were entered into the database before February 12), as well as sources of infection and routes of spread, located in the GISAID EpiFlu database.

"A new type of coronavirus entered the Huanan Seafood Market from elsewhere and quickly spread both within the market and beyond," the statement said.

Also, scientists found that the spread of the disease went at least three routes.

Scientists conducted a study of 58 haplotypes that were identified in these 93 samples, and found that a "zero patient" could infect someone on "Huanan", and the crowded seafood market with poor sanitary conditions became a favorable environment for the spread of the virus between people …

The study showed that the identified haplotypes can be conditionally divided into five groups, three of them are "old" spreading epidemics (for example, H1, H3 and H13), two are "new" (H56 and mv2). For example, in the samples of all patients with coronavirus who were related to the seafood market, the H1 haplotype and its derivatives H2 and H8-H12 were identified, and in the samples of some patients in Wuhan, the H3 haplotype was identified, which has nothing to do with the seafood market.

The conclusion, based on the timing of the onset of patient infections and the expansion of the disease, confirmed the theory that the Huanan market was not the source of the coronavirus. This is indicated by traces of "old" haplotypes H13 and H38 in samples from patients from Shenzhen (first case in Guangdong province) and Washington (first case in the United States). Their travel histories indicate that they must have contracted the infection during visits to relatives in Wuhan from late December 2019 to early January 2020.

At the same time, the scientists noted, haplotypes H13 and H38 were not detected in patient samples in Wuhan, probably because the samples existing in the database were predominantly collected from certain hospitals in the city from December 24, 2019 to January 5, 2020. If these two haplotypes can be found in patients in other hospitals in Wuhan, then this will be extremely useful for finding the source of the coronavirus.

Human-to-human transmission of the virus may have started as early as early December or late November 2019, and then accelerated when it reached the Huanan Seafood Market, the study points out.

The National Center for Disease Prevention and Control of China introduced a second level of emergency response to public health emergencies on January 6, which served as a warning against travel and mass gatherings. According to scientists, if more attention was paid to this warning and the public reaction was more active, then the level of spread of the disease in China and around the world in mid-January would be lower.

It was possible to establish that cases of infection in the other nine provinces of China and 11 countries were mainly directly related to Wuhan. At the same time, three possible sources of infection were identified in Guangdong province, two more in Chongqing and Taiwan. At the same time, it has been proven that patients from Australia, France, Japan and the United States had at least two sources of infection.

According to scientists, the H56 haplotype deserves special attention, which became the source of infection for patients in Australia, the USA, France and Taiwan.

The study noted that the general database contains few samples of patients from other countries (other than those indicated) and most of them have the same source of infection, the patients either became infected in Wuhan, or from people who were in Wuhan, or were infected in Guangdong, Singapore and other places.

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