Researchers believe they have documented the first instance of a human contracting COVID-19 from white-tailed deer in Ontario, Canada, according to findings published Feb. 25 in the preprint server BioRxiv.
The study involved analysis of nasal swabs and lymph node samples taken from white-tailed deer in Southwestern and Eastern Ontario hunted between Nov. 1 and Dec. 31. Researchers found 17 of 298 deer were positive for a "new and highly divergent lineage of SARS-CoV-2."
After comparing the virus strain found in the deer to that of the virus found in humans in the region, "We also identified a single human case that was very similar to our deer samples and came from the same time frame and region as the deer samples," Finlay Maguire, PhD, study author and assistant professor of community health and epidemiology at Dalhousie University in Nova Scotia, tweeted Feb. 26.
Dr. Maguire added that having so few samples made it difficult to fully understand the relationship between the genomes, but the "spatiotemporal link and known close contact with deer means this presents a potential deer-to-human transmission event."
There has been no evidence of additional human cases related to the strain so far, and available data indicated it's unlikely the variant could escape vaccines, researchers said.
"Together, our findings represent the first evidence of a highly divergent lineage of SARS-CoV-2 in white-tailed deer and of deer-to-human transmission," the researchers concluded.
Health experts in the U.S. have expressed concern over the possibility that white-tailed deer may become a reservoir for the virus to mutate and spread to other animals or back to humans in the form of a new variant. Separate preliminary findings published Feb. 7 found white-tailed deer on New York's Staten Island infected with omicron, the first time the strain had been detected in wild animals in the U.S. There are still a number of unanswered questions surrounding the virus's spread among deer, such as how they contract the virus and how the pathogen might mutate inside the host.