40% of US wild deer have COVID-19 antibodies

A newly published study shows that 40 percent of sampled wild white-tailed deer in the United States have antibodies for the novel coronavirus.

"The possibility exists for the emergence of new animal reservoirs of SARS-CoV-2, each with unique potential to maintain, disseminate and drive novel evolution of this virus," stated the paper on bioRxiv, an online archive and distribution service for unpublished preprints in the life sciences.

Such evolution could "lead to adaptation, strain evolution, and reemergence of strains with altered transmissibility, pathogenicity, and vaccine escape", according to the paper, which has yet to be peer reviewed.

The scientists chose white-tailed deer to assess such risk because they are abundant in North America, especially in the eastern region near urban centers. These deer have AEC2 receptors with high affinity for SARSCoV-2 which causes COVID-19.

Susan Shriner, a researcher at the US Department of Agriculture in Colorado, and her colleagues received more than 600 deer blood samples from Michigan, Pennsylvania, Illinois and New York from the National Wildlife Disease Program.

From January to March this year, 385 samples were collected and 152 of them were found to have antibodies to the coronavirus. The positive rate for 2021 varied from state to state, with the lowest rate at 7 percent in Illinois and the highest at 67 percent in Michigan. The rate for New York is 31 percent and for Pennsylvania at 44 percent.

Positive samples

In addition, three samples collected in January 2020 and one sample collected in 2019 were also found positive with the antibody. No positive antibodies were detected among samples between 2011 and 2018.

The scientists hypothesized that multiple activities could bring the deer into contact with people, including field research, conservation work, wildlife tourism, wildlife rehabilitation, supplemental feeding and hunting. In addition, contaminated water sources could be another transmission route.

Deer are not the only animals found to be infected with SARS-CoV-2. Last year, more than 15,000 farmed mink died from the coronavirus in the US. Scientists have only identified direct transmission of the virus from infected humans to mink as the only definitive transmission route.

The scientists recommend to continue and expand wildlife surveillance to determine the significance of SARS-CoV-2 in free-ranging deer, as well as in their predators and scavengers to detect and identify potential variants.