Scientists have identified a new, highly mutated version of the coronavirus in white-tailed deer in southwestern Ontario, one that may have been evolving in animals since late 2020.

They also found a very similar viral sequence in one person in the area who had close contact with deer, the first evidence of possible deer-to-human transmission of the virus.

“The virus is evolving in deer and diverging in deer away from what we are clearly seeing evolving in humans,” said Samira Mubareka, a virologist at Sunnybrook Research Institute and the University of Toronto and an author of the new paper.

The report has not yet been published in a peer-reviewed journal, and there is no evidence that the deer lineage is spreading among, or poses any elevated risk to, people. Preliminary laboratory experiments suggest that the lineage is unlikely to evade human antibodies.

But the paper was posted online just days after another team reported that the Alpha variant may have continued to spread and evolve in Pennsylvania deer even after it disappeared from human populations.

Together, the two studies suggest that the virus may be circulating among deer for extended periods of time, raising the risk that the animals could become a long-term reservoir of the virus and a source of future variants.

“There’s certainly no need to panic,” said Arinjay Banerjee, a virologist at the University of Saskatchewan who was not involved in either study.

But, he added, “The more hosts you have, the more opportunities the virus has to evolve.”