A new variant of the coronavirus found in white-tailed deer in Canada was later discovered in a person who lived nearby and had contact with the deer population, according to a recent study. The researchers say it’s possible the deer transmitted the virus to the human.
Emerging evidence that COVID-19 is gaining a foothold in wildlife could have negative long-term consequences for humans, according to Nükhet Varlik, associate professor of history at Rutgers University-Newark.
“Even if we managed to vaccinate the entire human population, the disease can still come back — from the animals back to us — which is, in fact, what happened with some of the other historical pandemics,” Varlik says. “So, in the long term, I don't think COVID can be eradicated, to be honest.”
Six out of every 10 infectious diseases in people are zoonotic, meaning they pass between species, from animals to humans.
Examples of zoonotic viruses include the flu, West Nile virus, the plague, rabies and Lyme disease.
The coronavirus outbreak has been linked to a market in Wuhan, China, where live animals were slaughtered on site. And although the virus is classified as zoonotic, no animal reservoir of the disease has been found.
Any new COVID-19 variant that animals might pass back to humans has the potential to mutate into something totally new.
“It's definitely going to evolve differently in an animal than it will in a human,” says Cody Warren, a virologist and immunologist who is a postdoctoral fellow at the University of Colorado Boulder. “Now we have what we're considering a human virus trying to evolve to grow in an animal, and so, it's going to undergo its own unique evolutionary trajectory in that animal.”
Multiple COVID-19 variants such as delta and omicron have been found in humans, and scientists cannot rule out the possibility that some variants came from animals.
“Most of the attention and resources are focusing on, ‘How do we test humans?’ and ‘How do we coordinate hospital beds?’” says Suresh Kuchipudi, a professor and chair of emerging infectious diseases at Pennsylvania State University. “But, in this process, we haven't really been looking at animals. …That's why we have a lot of missing links to trace back the origins of these viruses. So, it may be that we haven't been looking into some animal species in some part of the world where this evolution largely may have happened. We have lots of gaps in connecting the dots.”
Kuchipudi, a veterinary virologist, co-authored a separate study that found evidence of COVID-19 in white-tailed deer in Staten Island, New York. Researchers tested the animals between December 12, 2021, and January 31, 2022, and found COVID-19 antibodies in 19 of the 131 animals sampled.
When a virus goes from humans back into animals, the process is referred to as spillback.
“And what I think is most concerning about that is that it gives new opportunities for the virus to evolve in new, unique and innovative ways,” says Warren. “And that virus could potentially evolve in a way and then jump back into humans and spread again throughout the human population as a new disease.”
Kuchipudi emphasizes the need to begin monitoring high-risk animals where the force of infection is high and based on their frequent exposure to humans in order to stop, or at least minimize, transmissions from animals to humans.
“Then we can track down what is happening in terms of the virus evolution. But will we also be able to determine what are the routes through which this exposure has happened? Is it through wastewater or leftover food?” says Kuchipudi. “Although we found deer have the virus, it is not entirely clear how the free-living deer, that don't really come close to humans typically, are picking up the infection.”
Right now, there is no coordinated, concerted effort nationally or internationally to address the problem of COVID-19 in animals, according to Kuchipudi. But he is hopeful that is changing. The American Rescue Plan provides $300 million for the monitoring and surveillance of animals believed susceptible to COVID-19.
“I see a lot of momentum happening,” Kuchipudi says. “A lot of relevant people recognize this is a problem. And I think most federal and state agencies are very seriously discussing looking into this.”