The risk of SARS-CoV-2, the virus that causes COVID-19, spilling back into the human population from animal hosts appears to be waning in the northeastern United States, according to fresh research. While the virus continues to evolve in humans, its ability to infect and spread among animals seems to be diminishing, offering a measure of reassurance as we navigate the ongoing pandemic. This shift is the result of surveillance studies conducted by a collaborative team of researchers from UConn, Yale University, and the Connecticut Agricultural Experiment Station.
The findings, recently published in Scientific Reports, suggest that successive variants of SARS-CoV-2 may be losing their affinity for non-human animals. This is a significant development, as earlier in the pandemic, concerns were raised about the potential for animal reservoirs to fuel new outbreaks. The initial detection of the virus in a dog in Connecticut in 2021, confirmed by the Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL), highlighted the virus’s capacity to cross species barriers.
Researchers analyzed nearly 900 samples from a variety of wild and domestic animals, including cats, dogs, ferrets, woodchucks, and cattle. “We looked at a large number of wildlife [samples],” explained Guillermo Risatti, director of the CVMDL and professor of pathobiology and veterinary science at UConn. “We have incredibly limited agriculture in Connecticut. But there could be a risk because of the wildlife infringement we have.” The samples, collected through routine diagnostics and targeted studies, were tested for the presence of coronaviruses.
Surveillance Reveals Decreased Viral Presence
The study revealed several kinds of animal coronaviruses in samples from seven different species, but none contained SARS-CoV-2. To further investigate, researchers conducted laboratory experiments, infecting white-footed mice with both the original strain of SARS-CoV-2 and the Omicron variant. While the mice were susceptible to both variants, they shed less of the Omicron variant and did not transmit it to each other. Notably, the original strain was capable of spreading among the mice, but neither variant successfully jumped to another species, such as hamsters.
“This is decent news as this reduces the chance of spillback of newly evolved animal variants into humans,” said Caroline Zeiss, professor of comparative medicine and of ophthalmology and visual science at Yale School of Medicine and senior author of the study. She emphasized the importance of continued monitoring, stating, “Ongoing monitoring is essential, particularly for viruses that are capable of infecting many species such as corona and influenza viruses. Long-term surveillance of wildlife and animals living close to humans gives us a unique chance to spot new pathogens that might spread to humans or affect animal health.”
The ‘One Health’ Approach
The research underscores the importance of a “One Health” approach, recognizing the interconnectedness of human, animal, and environmental health. Risatti hopes the CVMDL will become a regional center for emerging disease surveillance, fostering collaboration between animal and public health sectors. “The idea is to bring this to UConn and make it a center for the northeast for emerging diseases in animal health and public health,” he stated.
The study was funded by the United States Department of Agriculture and the Centers for Disease Control and Prevention, highlighting the federal commitment to understanding and mitigating the risks posed by zoonotic diseases – those that can transmit between animals and humans. This research builds upon earlier findings that demonstrated the virus’s ability to spread within certain animal populations, such as white-tailed deer and mink, raising concerns about potential mutations and re-introduction into the human population.
While the findings offer a positive outlook regarding the immediate risk of animal-to-human transmission of SARS-CoV-2, researchers caution that the threat of emerging infectious diseases remains constant. Continued surveillance and investment in diagnostic capabilities are crucial for protecting both animal and human health. The CVMDL continues to offer COVID-19 testing collection kits for $15.00, as of February 16, 2026, according to their website (https://cvmdl.uconn.edu/covid-19-testing-information/).
Looking ahead, the researchers emphasize the need for sustained vigilance and proactive surveillance to identify and address potential threats from novel pathogens. The lessons learned from the COVID-19 pandemic underscore the critical importance of a collaborative, multidisciplinary approach to safeguarding public health.
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