Findings challenge standard understanding of COVID-19 infection

Some viruses move between species. For example, SARS-CoV-2, the virus that causes COVID-19, can spill over from humans to mink, an agricultural species, and then spill back from mink to humans. Spillback is a concern because SARS-CoV-2 can mutate in the mink and come back to humans in a more virulent form. Both spillover and spillback of SARS-CoV-2 have been reported on mink farms in the United States and Europe.