As scientists find more animal coronaviruses, they will be able to detect more and more parts of SARS-CoV-2 that are spreading among them. The researchers were also able to reconstruct some of the evolutionary steps that SARS-CoV-2 took to develop into a potential human pathogen while it was still infecting animals.

This pattern is likely to be followed by many viruses that have a heavy impact on human health today. HIV, for example, most likely originated in the early 1900s when hunters in West Africa became infected with viruses that infected chimpanzees and other primates.

However, some scientists felt it was too early to conclude that something similar happened in the case of SARS-CoV-2. After all, the coronavirus first emerged in the city of Wuhan, which is home to the Wuhan Institute of Virology, where researchers are studying dozens of coronavirus strains collected in caves in southern China.

Still, it could be a coincidence that a top laboratory studying this family of viruses is located in the same city where the epidemic occurred. Wuhan is an urban hub that is larger than New York City and has a steady stream of visitors from other parts of China. There are also many large markets dedicated to wildlife from all over China and beyond. When wild animals are kept in confined spaces, viruses have the ability to jump from species to species, sometimes leading to dangerous recombinations that can lead to new diseases.

Research in this laboratory began after another coronavirus led to the SARS epidemic in 2002. The researchers soon found relatives of this virus, called SARS-CoV, in bats and civets sold in Chinese markets. The discovery opened scientists’ eyes to any animal coronavirus with the potential to cross the species line and start a new pandemic.

Virologists can take many steps to reduce the risk of infection with the viruses they are studying. But several accidents have happened over the years. Researchers got sick and infected others with their experimental viruses.

For example, in 2004 a researcher at the National Institute of Virology in Beijing was infected with the coronavirus that causes SARS. She passed it on to others, including her mother, who died of the infection.