Americans have transmitted COVID-19 to wild deer hundreds of times, an analysis of thousands of samples collected from the animals revealed, and people have also caught and spread mutated variants from deer at least three times.
The analysis published Monday stems from the first year of a multiyear federal effort to study the virus as it has spread into American wildlife, spearheaded by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service, or APHIS.
Scientists analyzed 8,830 samples collected from wild white-tailed deer across 26 states and Washington, D.C., from November 2021 to April 2022, to study the COVID variants that had infected 282 of them.
By comparing sequences from the viruses in deer against other publicly reported samples from databases of human infections around the world, they were able to trace the likely spread of these variants between humans and animals.
A total of 109 “independent spillover events” were identified, matching viruses spotted in deer to predecessors it likely descended from in previously infected humans.