Ciervos infectados con COVID-19 podrían convertirse en reservorio del virus y alterar la pandemia

A growing body of research from American universities has raised an unsettling possibility: white-tailed deer, abundant across the United States, may have become a permanent reservoir for the coronavirus, fundamentally altering the trajectory of the pandemic itself.

The concern emerged gradually. Since COVID-19 first spread globally, theoretical models suggested the virus could bind easily to deer cells and establish infection. But theory became alarming reality when researchers began testing actual animals. The National Academy of Sciences reported that 40 percent of tested deer had developed antibodies against the virus, evidence of past infection. More troubling still, veterinarians from the University of Pennsylvania discovered active COVID infections in roughly 30 percent of white-tailed deer sampled in Iowa. During a cold spell between late November and early January, that figure spiked to nearly 80 percent—a rate fifty to one hundred times higher than infection levels among Iowa's human residents at the same time.

What makes this discovery genuinely consequential is what it could mean for the future. If deer become what scientists call a viral reservoir—a permanent animal host where the virus circulates indefinitely—the implications are stark. Suresh Kuchipudi, the Pennsylvania veterinarian who co-led the research, explained the stakes plainly: if the virus finds a non-human home, it creates a safe harbor where coronavirus can keep spreading even after the entire human population becomes immune. The hope of eliminating or eradicating COVID-19 in the United States, and by extension globally, would essentially vanish. "It makes it increasingly difficult to control or even eradicate the virus," Kuchipudi told NPR.

The speed of transmission among deer populations startled even the researchers. Vivek Kapur, the microbiologist who co-directed the Pennsylvania study, said the sheer number of positive samples caught them off guard. Between April and December of the previous year, 30 percent of sampled deer tested positive. But when winter arrived and temperatures dropped in Iowa, the infection rate climbed dramatically. The viral variants circulating in the deer were genetically identical to those spreading among humans, indicating that people had infected the animals, who then transmitted the virus among themselves.

The concern extends beyond mere persistence. Linda Saif, a virologist at Ohio State University's College of Veterinary Medicine, worries the virus could spread to all thirty million white-tailed deer estimated to live across the country. But her deeper fear involves evolution. As the coronavirus circulates within the deer population, it could mutate and generate new variants entirely. This scenario has already played out in Europe. In mink farms in the Netherlands and Poland, infected animals became breeding grounds for viral mutation. The virus jumped from farmers to mink, then mutated as it spread through the animals, and eventually returned to humans in altered form—potentially more dangerous than before.

Saif raised additional questions that remain unanswered: Can the virus jump back from deer to humans? Could infected deer transmit COVID to livestock grazing nearby? The uncertainty itself is troubling. "If these answers are yes, they are obviously concerning," she said. The risk is not merely that the virus persists, but that it evolves in ways we cannot predict or control.

This is why constant surveillance of COVID-19 in both wild and domestic animal populations has become essential, Kuchipudi emphasized. Without vigilant monitoring of potential reservoirs like deer, a dangerous new variant could emerge suddenly, catching public health officials unprepared. The pandemic, it seems, may not end when human immunity reaches sufficient levels. It may simply relocate, finding refuge in the forests and fields where millions of deer roam.