White-tailed deer on Staten Island are the first wild animals found to be carrying the highly transmissible Omicron variant of the coronavirus. The discovery has raised new concerns that the species could host new Covid-19 strains that could eventually spill over to humans.
Scientists already knew white-tailed deer could test positive for the virus, but until now they weren’t sure if the species could contract the Omicron variant. The first case of a deer with Covid-19 was in Ohio in August 2020, and a study published last November reported that up to a third of free-living and captive deer in Iowa carried traces of the virus.
To test the animals on Staten Island, the research team temporarily captured and took blood and nasal samples from 131 wild deer. In their study, which has not yet been peer-reviewed, the team notes that swabs were collected between December 2021 and January 2022 when the Omicron variant was surging among nearby human residents. They found that around 15 percent of the white-tailed deer they sampled tested positive for coronavirus antibodies, and some had antibodies for the Omicron variant.
“We demonstrated for the first time that the omicron variant has also spilled into the wild animal species," Suresh Kuchipudi, a professor of virology at Penn State and lead author of the study, told Mary Kekatos for ABC News. "The fact that the spillover continues to happen is quite concerning."
One deer had both an active infection and very high antibody levels, suggesting the animal might have been reinfected with the virus, according to Gizmodo’s Ed Cara.
So far, there is no evidence that deer are transmitting Covid-19 to humans, but because deer are widely abundant across the United States, some experts worry the animals could become a reservoir for new Covid-19 variants or lead to new mutations. As the virus spreads, it has the potential to take on unpredictable changes. Those mutations could contribute to a variant that poses an even more serious health risk.
“You can imagine this could be a never-ending, perpetual cycle of deer constantly circulating the virus among themselves and picking up the new variants,” Kuchipudi tells the New York Times’ Emily Anthes and Sabrina Imbler.
Because the Omicron variant found in the Staten Island deer has a close genetic resemblance to strains found in nearby humans, it’s likely people are a source of the deer infections. Scientists still aren’t sure how the deer are contracting coronavirus, perhaps through contaminated wastewater or close contact with infected humans. Though current variants don't appear to jump from deer to humans, monitoring how the virus spreads through deer populations could be critical for public health.
“The circulation of the virus in deer provides opportunities for it to adapt and evolve,” says Vivek Kapur, a veterinary microbiologist at Penn State University, who is part of the research team, to the New York Times. “And it’s likely to come back and haunt us in the future.”