(WAND) - COVID-19 has been transmitted from people to deer in multiple states, research shows. 

According to NBC News, scientists in Ohio swabbed nostrils of white-tailed deer and discovered humans spread the virus to deer at least six times. The study was published in Nature. 

The research shows about a third of sampled deer had active or recent infections. There was similar research done in Iowa, which involved the examination of tissue from roadkill and hunted deer, that found widespread COVID-19 evidence. 

The deer population in the United States is estimated at about 30 million, per the Association of Fish and Wildlife Agencies, and the research suggests COVID-19 could be taking hold among them. Scientists have said they have not seen evidence of the virus spreading from deer to people, but noted it could happen. 

Scientists said there could be a risk to humans if there is a new variant created from mutations in deer. In addition, they said wild animals with the virus could retain variants that aren't circulating among people, allowing them to come back later on. 

Suresh Kuchipudi, a Pennsylvania State University virologist, told NBC News it is "very unsettling" that the possibility of such things happening exists. 

“We could be caught by surprise with a completely different variant," Kuchipudi said.Â