In late December 2019, the Wuhan City Health Commission reported an unidentified case of the virus. pneumonia, Along with other reports, warned the World Health Organization (WHO) about potential new health threats identified as follows: coronavirus In January 2020, it was later named SARS-CoV-2.
However, it was revealed that the virus appeared before late December 2019, and in some cases months ago.Joint WHO research According to Chinese and international researchers, 174 SARS-CoV-2 infections were confirmed throughout December, with the earliest on December 8. Most researchers believe that the virus broke out sometime in the fall or winter of 2019, but it’s difficult to pinpoint the exact time. More data. Knowing when SARS-CoV-2 began to spread among people may help prevent or combat future epidemics. Pandemic By providing insight into the types of disease surveillance that would have been needed to prevent this, according to experts.
Sergei Pond, a professor of biology at Temple University in Philadelphia, said the virus had already spread considerably by the time it was identified and was difficult to contain. “I don’t want to wait eight weeks for the cases of abnormal pneumonia to concentrate,” Pond said. “You want to have a surveillance system that picks it up very quickly.”
Related: Seven facts about the origin of the new coronavirus
The first clinically confirmed case of COVID-19 was a man who began to experience symptoms on December 8, 2019. The Washington Post reported.. Earlier reports suggested that the first case could be traced back to December 1st or November 17th, Live science previously reportedJoel Wertheim, an associate professor at the University of California, San Diego, said these reports were not confirmed in a joint study between WHO and China. Wertheim and his colleagues analyzed the genetic information of the virus and performed epidemiological computer simulations. As a result, the virus outbreak date is between mid-October and mid-November 2019. Chemistry..
To draw this conclusion, researchers analyzed the SARS-CoV-2 genome from the first wave of a pandemic in China.because virus Researchers may have accumulated genetic changes over time, identified a percentage of genetic mutations, and the first person with a relatively unchanged form of the virus began to spread it to people. I was able to go back until I discovered that there was. Researchers estimated that for SARS-CoV-2, the date would be between November 17, 2019 and December 20, 2019.
But that’s just when the virus began to spread among people. Because it’s SARS-CoV-2 Derived from animals And the animal coronavirus that was passed to humans and first infected the first person may have a genetic difference from the current virus. That version may have taken some time to be genetically recognized as SARS-CoV-2. This means that the virus may have begun to spread even faster.
To see how long it took the virus to accumulate these types of changes, researchers used computer simulations of the spread of the virus. They concluded that the most common result was 8 days, but this process is likely to take 0 to 41 days. The process may have pushed back the initial spread of the virus in mid-October, they said.
Wertheim emphasized that the purpose of this study was to see how far back the virus was. can It started to spread, but not always early did expand. “That’s as far as you can go, and yet it’s a lot of assumptions to get it back,” he said.
Based on current data, many researchers, including the pond, will agree that there is likely to be a time frame proposed by Werthheim and his colleagues in the study, the pond said in the early evolution of SARS-CoV-2. Published in a journal in May, stating that he co-authored another study examining the history of Molecular Biology and Evolution.. In that study, Pond and his colleagues used a type of genetic analysis that was first developed to reconstruct the evolution of human cancer cells. They determined that the version of SARS-CoV-2 that spread in December 2019 would take 6-8 weeks to evolve from the first human strain of the virus. The method they used was different, but that time frame will also push back its origins at about the same time as other studies, that is, October 2019.
But Pound said there was also a way to gain new insights into when the virus appeared. For example, many believed that the virus originated from animals at the Wuhan South China Seafood Wholesale Market, but subsequent analysis found cases that could not be associated with the market. Live science previously reported.. In contrast, Wertheim said the lack of confirmation from a joint study between China and WHO on the December 1 and November 17 cases used in his study could affect the estimates. .. Frozen blood samples from early potential cases or gene sequence records may also provide additional insights, Pond said.
“It’s easy to imagine a scenario where you get an additional 5 or 10 sequences early on and they just change everything,” he said. Anyway, Pond believes the virus is unlikely to appear before the fall of 2019, or at the end of the summer of 2019 at the earliest. Because the virus begins to spread, becomes extinct, and then reintroduces — very unlikely and more and more.
Some studies suggest a start date before October, but the study has not been peer-reviewed and published in scientific journals. In one like that study, Harvard University researchers analyzed Internet searches in Wuhan, China from 2019,diarrhea“In August 2019, there was a correlation with the increase in traffic in the parking lot of Wuhan Hospital in the same month. Diarrhea is more common with COVID-19 Rather than the flu, researchers suggested that this increase might indicate that the virus would spread in August.
and Commentary However, in response to that study, other researchers pointed out that the author used a nasty Chinese translation for “diarrhea” and that search terms were used not only in Wuhan but throughout China. ..Another survey published on the preprint server medRxiv No peer review was conducted and traces of SARS-CoV-2 were found in the wastewater of Barcelona, ​​Spain in March 2019. However, the findings were of little significance without the evidence that the patient experienced. Symptoms of COVID-19 In Barcelona at that time.
Attempting to find a more accurate starting date creates unique problems. According to Wertheim’s analysis, the virus may not have been detected in the early stages due to the very small number of cases. In fact, in computer simulations from studies modeling the spread of SARS-CoV-2 from a single human case, the virus was extinct most of the time, and when it was not, it was sometimes one person. Depends on to spread it more widely again. Of course, in a densely populated metropolis like Wuhan, that scenario doesn’t matter. It is easy for one person to infect many with the virus. However, it is possible that few people are infected with the virus early on.In a tough situation influenza Since the season, and SARS-CoV-2 had a relatively low mortality rate compared to viruses such as Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS), Wartheim was the first virus to He said it was natural that it wasn’t detected when it started.
Wertheim hopes that systems that enable early detection will help prevent or mitigate the effects of future pandemics.
“In an ideal world, there would be a kind of systematic and interrelated way to report all unexpected illnesses in a way that can be seen across borders,” he said. “Something like that would have allowed us to step into this pandemic and potentially stop it on that track.”
Originally published in Live Science.
