Researchers at Cornell University have identified that variants of COVID-19 that no longer spread among people continue to circulate in white-tailed deer. The study details were published in the Proceedings of the National Academy of Sciences.
Biologists collected 5,700 deer lymph node samples between 2020 and 2022 across New York State. Beyond detecting alpha, beta, and gamma variants of SARS-CoV-2 in deer, they observed numerous mutations in the virus genome. This pattern suggests the virus could have circulated within animal populations for months before being detected in humans again.
At the time the study was conducted, these Deer-associated variants had not been circulating in humans for four to six months. Possible routes of infection for deer include hunting, wildlife rehabilitation, wildlife feeding, and sustained human contact through contaminated sewage systems.
Scientists propose that the mutations observed in the virus might have facilitated easier transmission among deer. In effect, the virus, originally spreading from an animal reservoir in Asia to humans, appears to have established a new wildlife reservoir in North America.
White-tailed deer are the most abundant large mammals in North America, numbering more than 30 million in the United States. A separate study from 2022 reported the presence of COVID-19 in about 40% of white-tailed deer. Presently, researchers remain uncertain whether deer can act as long-term reservoirs for these older variants. Nevertheless, the findings emphasize the value of ongoing surveillance of the virus within deer populations and the predators that hunt them. ”