Cornell study finds white-tailed deer carry variants of SARS-CoV-2

A study by researchers at Cornell University has found that white-tailed deer are carrying variants of SARS-CoV-2 that, at one time, circulated among humans but are currently extinct.

According to a report by the Cornell Chronicle, the study is called the “Proceedings of the National Academy of Sciences” and researchers found that three variants of concern are co-circulating in white-tailed deer in New York state. The variants are alpha, gamma and delta. The study showed the animal population could be a wildlife reservoir for the variants. 

Scientists do need to study more to determine whether deer could be long-term reservoirs for the once obsolete variants, but the findings suggest the virus has found a new wildlife reservoir in North America.

“A virus that emerged in humans in Asia, most likely after a spillover event from an animal reservoir into humans, apparently, or potentially, has now found a new wildlife reservoir in North America,” said Diego Diel, an associate professor in the Department of Population Medicine and Diagnostic Sciences and director of the Virology Laboratory at the College of Veterinary Medicine’s (CVM) Animal Health Diagnostic Center, in the report.

According to the report, the deer have become infested with the virus throughout the COVID-19 pandemic due to contact with humans through hunting, wildlife rehabilitation, feeding wild animals or through wastewater or water sources. The study adds, however, that no one yet knows the true definitive reason.

The study is reportedly one of the most comprehensive assessments of the virus’ prevalence, genetic diversity and evolution in white-tailed deer. The researchers tested more than 5,700 samples of deer lymph tissues that were collected over two years and also found potential hotspots of infection across New York state. 

They also found seven clusters where samples from a certain geographic area contained the same variant. Researchers compared the genomic sequences of the variants found in deer with those taken from humans and also found the viruses had mutated in the deer. This suggests the variants have been circulating for months.

Diel said that the study's most striking finding was the detection of co-circulation of the three variants of concern. The viruses' mutations suggest that the virus has adapted to deer, possibly making it more transmissible between them.