The coronavirus pandemic almost did not occur, according to a new study.
Researchers battling to find out when and how the virus first appeared in China estimate that the first human was probably not infected until October 2019 at the earliest.
And their models showed something else: The virus almost managed to develop into a pandemic.
Only bad luck and suffocating conditions at the Juan Seafood Market in Wuhan - the place where the pandemic appears to have started - gave the virus the advantage it needed to spread around the world, the researchers said in the journal Science.
"It was a perfect storm. If things were a little different, if the first person to bring the virus to Juanan market had decided not to go that day, or even if he was too ill to go and just stay at home, this or other early hyper-transmission events may not have happened. "We may never have learned about the coronavirus," Michael Warobi, a professor of evolutionary biology at the University of Arizona, told CNN.
The research team applied the method of molecular dating, studying the percentage of ongoing mutations to calculate how long the virus has been around.
They also used computer models to show when it could have spread and how it spread.
"Combining the different indications, we were able to set a ceiling in mid-October 2019, when SARS-CoV-2 was launched in Hubei Province," said Joel Vertim, an associate professor in the Department of Infectious Diseases and Global Public University. .
There have been reports from Italy and other European countries that the virus may have infected people there before October. However, the new study published last Thursday shows that about 10-12 people were infected between October and December.
The study shows that the virus first appeared in China's Hubei province and not elsewhere, the researchers said.
"Our results also contradict allegations that a large number of patients needed hospitalization because of COVID-19 in the province of Hubei before December 2019 ", wrote the authors of the study
From the few cases at the end of 2019, the virus has spread around the world. According to Johns Hopkins University, 122,8 million people worldwide have been infected so far.
The study, however, did not identify which animal was the source of the coronavirus. Genetic evidence suggests that bats carry a closely related virus, and also suggest that another intermediate species of animal probably became infected and transmitted the virus to a human somewhere.
This is what happens, in general. The U.S. Centers for Disease Control and Prevention regularly monitors and records cases of new strains of influenza that infect people attending county fairs and interacting with pigs, for example.
But so far, none of these infections have led to an epidemic or even a pandemic.
What is needed is an infected person and a lot of contact with other people - like in a seafood market full of people. "If the virus is not lucky enough to find these circumstances, even a well-adapted virus can disappear," says Warobi.
"These events probably happen much more often than we realize. "They just do not evolve and we never hear about them."
And that could have happened to her Covid-19.
"What could have happened in this case was that the virus was in a very small number of people in October, November and December, until it entered this seafood market in Juan," Warobi said.
It is possible that this market was not the place where the virus first appeared, but exactly where it strengthened.