The mystery of the source of the new crown virus to be solved

Source: Zhonggong Net - Workers Daily

Liang Fan

Since the outbreak of covid-19, medical researchers around the world have embarked on painstaking research into the origin of the virus.

With the joint efforts of nearly a year, the world has a new understanding of the "source" and "flow" of the new crown virus that is different from before.

But so far, the work is still continuing, and no final conclusion has been reached.

One

According to Italian media reported on January 11, from a biopsy sample of a female skin disease patient in the country on November 10, 2019, an international research team led by the University of Milan in Italy found the genetic sequence of the new crown virus.

This result brought forward the appearance of "Patient Zero" in Italy to November 2019 again.

The leader of the research team, Giannotti from the University of Milan, told the media that in the next study, samples of new coronavirus infections that are earlier than in November 2019 may be found.

He said the study found that some cases of infection with the new crown virus only showed skin disease symptoms, so they wanted to know whether anyone with skin diseases before the outbreak of the new crown epidemic had already been infected with the new crown virus.

In November last year, researchers at institutions such as the National Institute of Cancer in Milan, Italy, published a paper in the country's Journal of Oncology saying that the new crown virus may have spread in Italy as early as September 2019, which is several months before Italy reported its first confirmed case of new crown.

Similar situations have been found in many countries around the world.

The results of the study released by the health department of the state of Espírito Santo in southeastern Brazil on the 12th confirmed that as early as the middle of December 2019, before the world's first new crown pneumonia case was confirmed, the state had already had new crown pneumonia infections, but the current test results showed that the epidemics such as dengue fever and chikungunya fever that appeared before February of that year hindered the diagnosis of new crown pneumonia cases.

On November 30 last year, researchers at the U.S. Centers for Disease Control and Prevention published a report in the semi-monthly journal Clinical Infectious Diseases that antibodies to the new coronavirus were already present in some American blood donation samples in December 2019, which means that the new crown virus may have appeared in the United States at that time, a month earlier than the time when the first confirmed case of new crown pneumonia was officially reported in the United States on January 21 last year.

Two

Researchers not only try to find clues to earlier coronavirus infection in humans, but also retrospective studies of wastewater, laboratory specimens, etc., also show that the new crown virus may have existed in many countries long before the outbreak.

Previously, Spanish researchers found traces of the new coronavirus in wastewater samples taken on March 12, 2019, but the level of the virus was very low.

This means that the coronavirus may have existed in Barcelona at the time, much earlier than the time when the first confirmed case of COVID-19 was reported globally.

In addition to Spain, Brazilian and Italian researchers also found traces of the presence of the new coronavirus in wastewater samples before the earliest confirmed cases were reported locally.

Genetic material from COVID-19 can be carried into wastewater by the excrement of infected people, and epidemiological studies based on wastewater can help better understand the spread of the virus.

On November 23 last year, the journal Nature published an article saying that coronaviruses closely related to the pandemic virus had been found in Japan and Cambodia, and that these viruses were found in bats stored in laboratory freezers, and that they were the first "relatives" of the new coronavirus found outside Of China.

Among them, the Cambodian research team found a close relative of the new coronavirus in bats stored in the laboratory refrigerator, which was found in 2010 in the body of the Shamel chrysanthemum bat captured in northern Cambodia.

In addition, a team of researchers in Japan also reported the discovery of another closely related coronavirus in frozen bat droppings. They found the virus in the small Japanese horned manta bat captured in 2013, named "Rc-o319", which has a genome sequence of 81.47% consistency with the new crown virus, and is also a "relative" of the new crown virus.

Three

On 23 November 2020, Michael Ryan, who is who's head of the Health Emergencies Programme, said at a regular briefing that the coronavirus could have infected a number of people at very early times, at different locations and times in the world.

Ryan noted that identifying the world's first infectious disease case is an important aspect of all epidemiological investigations. "There may be more than one first case [of COVID-19] because the disease is likely to have originated from the spread of several animals. A growing body of information indicates that the coronavirus was initially distributed across the globe. Researchers have recently discovered the virus in bats, and we've seen other potential sources of the virus in different places. ”

As for how the new crown virus can be transmitted across species and to humans, Michael Ryan said that it may be a single event or multiple events, which may occur at a certain time or over a long period of time, and it is uncertain whether humans or animals have transmitted the new crown virus.

WHO experts said in August last year that past experience showed that finding the animal origin of the new coronavirus and how the virus breaks down species boundaries can be time-consuming and difficult.

Despite the difficulties, medical workers around the world, led by WHO, are still working to unravel the mystery of the origins of the new crown virus. Ryan has said that WHO is working with scientists around the world to trace the origin of the virus and is open to information.

WHO's attitude towards the guiding ideology of the traceability of the new crown virus has always been clear and unambiguous.

On November 30 last year, WHO Director-General Tedros Adhanom Ghebreyesus said at a regular press conference that the traceability of the new crown virus is a scientific issue and that the politicization of the traceability of the new crown virus should be avoided.

Editor-in-charge: Xiao Tian