The WHO team searched for a host in early 2020, testing more than 80,000 animals from 209 species, including wild, domesticated and market animals. Not a single animal infected with SARS-CoV-2 was found. This finding strongly favors the lab-leak theory. We can only wonder if the results would have been different if the animals tested had included the humanized mice kept at the Wuhan Institute of Virology.