A deer may have passed COVID-19 to a person, study suggests

The virus is widely circulating in white-tailed deer. Until now, no humans are known to have been infected by deer. A white-tailed deer in Canada likely infected a human with coronavirus, according to new research. The case, reported in a preprint journal, would be the first known instance of a COVID-19 spillover from a white-tailed deer—a common species throughout North America—into another species. Previous work has shown that the virus is circulating widely in U.S. white-tailed deer populations. Before this latest report, however, the virus appeared to be very similar to that found in nearby humans, suggesting that the deer likely were sickened by us—not the other way around. Now, a team of 32 government and academic researchers in Canada has concluded in a new work posted in BioRxiv that in late 2021, more than a dozen white-tailed deer in Canada had been infected with coronavirus that had a constellation of “mutations that had not been previously observed among SARS-CoV-2 lineages.” What’s more, further analysis revealed that a person who had close contact with white-tailed deer in Ontario was infected with the same variant of coronavirus. (It was detected as part of Canada’s standard genomic sampling of all COVID-19 cases in the area at the time.) Together, those factors suggest that the virus had been circulating among deer and accumulated mutations as it hopped from one animal to the next, before ultimately being passed to a person. It’s possible the virus was transmitted first through another host species, such as a mink, though the genomic analysis suggests that direct transmission from deer to human is “the most likely scenario,” the authors write.