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The priority should be to “follow the animals”, starting at the Huanan market, says Eddie Holmes, a virologist at the University of Sydney in Australia. Given the large number of animal species that SARS-CoV-2 can infect, that sampling should be as expansive as possible, say researchers.

And it should definitely include bats. The closest known relative of SARS-CoV-2 is a bat coronavirus called RaTG13, isolated from a bat in a mine in Mojiang, southern China. But it shares only 96% of its genome with SARS-CoV-2, meaning that it is only distantly related. Courtier says that more bats should be sampled from that mine, and that researchers should share the sequences of other coronaviruses isolated there.

But Linfa Wang, a virologist at Duke–National University of Singapore Medical School, doubts whether closer relatives will be found, given the exhaustive sampling done in the cave by researchers over the past decade. “If you gave me a billion dollars, I would not sample in Mojiang cave. I would sample in Southeast Asia,” adds Wang, who says that sampling should extend to lesser-sampled regions such as Thailand and Cambodia, where other relatives of SARS-CoV-2 have recently been isolated.

More: https://www.nature.com/articles/d41586-021-00877-4