A joint WHO study by Chinese and international researchers identified 174 SARS-CoV-2 infections throughout December, with the earliest going back to Dec. 8. Though most researchers think the virus originated sometime during the fall or winter of 2019, an exact time is hard to pinpoint without more data.
Finding out when SARS-CoV-2 began spreading among people could help prevent or address future epidemics and pandemics by providing insight into the kind of disease surveillance that would have been necessary to prevent this one, experts say.
Because SARS-CoV-2 originated in an animal and was passed to humans, the animal coronavirus that originally infected the first person could have genetic differences from the current virus. That version might have taken a while to become genetically recognizable as SARS-CoV-2, meaning the virus may have started spreading even earlier, the researchers said.
To see how long it might have taken the virus to accumulate those kinds of changes, the researchers used a computer simulation of the virus’s spread. They concluded that the process likely would have taken anywhere from zero to 41 days, although the most common result was eight days. This process, they said, might have pushed back the virus’s initial spread to mid-October.
