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However, the spread of the virus started before 2019. at the end of December, possibly several months before that date. A joint WHO study involving scientists from China and the rest of the world showed a total of 174 cases of the SARS-CoV-2 virus in December of that year, the earliest on December 8. Although scientists believe that the virus appeared sometime in the fall or winter of that year, it is difficult to determine the exact date without more data. If it were possible to find out exactly when this virus began to spread among humans, it would be possible to prevent, or understand earlier, the outbreak of an epidemic or pandemic in the future.
Sergei Pond, a professor of biology at Temple University in Philadelphia, says that when the virus was finally identified, it was already quite widespread, making it difficult to control. “When an unknown variant of pneumonia spreads, you shouldn’t wait eight weeks,” he said. “We need a monitoring system that prevents this at a very early stage.”
The first case of COVID-19 was confirmed in a laboratory by a man who in 2019 began to feel symptoms on December 8, writes The Washington Post. Although there is evidence that the first case could have been recorded on December 1 or even November 17, experts from the joint WHO-China study have not confirmed those data, says Joel Wertheim, an associate professor of medicine at the University of California. Together with his colleagues, he analyzed the genetic information of the virus and performed computer epidemiological modeling, so the date of appearance of the virus varies between 2019. October and mid-November, the team wrote in the journal Science in April.
The researchers came to this conclusion by studying the genomes of China’s first pandemic wave, SARS-CoV-2. Because viruses store information about genetic alterations, the researchers were able to determine the rate of a genetic mutation and then review the previous information to find out exactly when the first person with a relatively unaltered form of the virus could pass it on to others. That is why the researchers found that the date of appearance of the virus could have been 2019. November 17 or December 20.
This was established when the virus began to spread between humans. SARS-CoV-2 is known to have originated in animals, and was only later transmitted to humans, so the first animal coronavirus infection in person may be genetically different from the current virus. It took time for the animal virus to be genetically recognized as SARS-CoV-2, which scientists say could have spread the virus even earlier.
To find out how long it took for the virus to adapt to the changes, the researchers used a computer simulation of the spread of the virus. It was concluded that this could have lasted between 0 and 41 days, but the most common result indicated that 8 days was sufficient. This means that the initial spread of the virus could have occurred even earlier, in mid-October.
Wertheim emphasizes that the goal of the study was to find out when the virus might have started to spread, but not necessarily to know how it started to spread. “From what we know, there are still a lot of assumptions,” he explains.
Many scholars, including Pond, agree that based on current data, the time frame proposed by Wertheim and his colleagues is likely, says Pond, who conducted a study with other scholars to find out. The early history of the evolution of SARS-CoV-2, published in Molecular Biology and Evolution in May. In the study, the researcher and his colleagues used a genetic analysis that was specifically designed to reconstruct the evolution of human cancer cells. It was concluded that SARS-CoV-2, which began to spread in December, would take 6-8 weeks to develop from the original human virus strain. Although a different method was used, it was finally found that the period of virus appearance would be the same as in the aforementioned study, 2019. October.
However, according to S. Pond, there are other ways to find out when the virus appeared. For example, many thought that the virus had been transmitted by an animal in the Wuhan meat and fish market, but a subsequent investigation found that there were cases outside the market. On the contrary, according to Mr. Wertheim, his investigation lacked the confirmation of a joint WHO-China investigation into the December 1 and November 17 cases, which could have affected the accuracy of Mr. Wertheim’s investigation. . More knowledge, according to S. Pond, could be provided and frozen by blood samples from early cases or records of genetic sequences.
“One can only imagine how things would change if we had 5 or 10 records of the first few sequences,” says Pond. However, the scientist said that it is unlikely that the virus appeared before 2019 in the fall, and the earliest possible date could be the end of the summer of the same year. This is because the more events that have allowed the virus to circulate in the environment, such as spread, disappearance, and reappearance, the further back in time, the more incredible it becomes.
There are also studies that claim that the virus appeared before October, but those studies have yet to be reviewed or published in scientific journals. In one such study, researchers at Harvard University analyzed the 2019 study the number of online searches in Wuhan and in August of that year found an increase in the number of searches for the keyword “diarrhea,” which also was correlated with the increase in the number of cars in the parking lots of the Wuhan hospital. Diarrhea is a common symptom of COVID-19 infection and not just the flu, so it was thought that it could mean that the virus would spread in August.
But commenting on the study, other scholars note that its authors used a rather strange translation of the word “diarrhea” into Chinese in their analysis, and that search for the word had increased throughout China at the time, not just in Wuhan. .
Another study, the preliminary version of which was published on the medRxiv server but not reviewed, states that traces of SARS-CoV-2 were found in the effluent in Barcelona, Spain, in 2019. March. However, the findings of this study were not based on any evidence that someone in Barcelona was experiencing symptoms of the virus at the time.
There are a number of problems trying to figure out when a virus appeared. Wertheim’s research shows that there were so few cases at first that the virus could not even be detected. In computer simulations that develop patterns of the spread of SARS-CoV-2 when only one person is infected, the simulation has shown most of the time that the virus should simply disappear. And even if it didn’t go away, it would often be up to just one person if it could spread again.
Of course, in a city as large and populated as Wuhan, this scenario doesn’t cause much of a problem – one person could actually transmit the virus to others. However, this shows that it is very likely that only a small percentage of people were initially infected with the virus. At the height of flu season, when mortality from SARS-CoV-2 was low compared to viruses such as severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS), Wertheim said it was not surprising. that once the virus started to spread, it was not observed.
The researcher hopes that systems that allow the virus to be detected more quickly will help prevent or mitigate the effects of pandemics in the future.
“Ideally, there should be some systematic and interconnected way of reporting unknown and unexpected diseases in a way that is understandable to other countries,” he said. “If something like this had existed, it would have helped us fight this pandemic and maybe even stop it.”
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