Researchers Raise Concern: Accelerated Evolution of COVID-19 Virus in Ohio’s White-Tailed Deer

New studies indicate that white-tailed deer in Ohio are harboring the virus responsible for COVID-19. Notably, the data shows that the rate of viral mutation is approximately three times faster in these deer compared to humans. The future implications of this phenomenon for cross-species transmission are yet to be ascertained.

Key Findings: Deer Serve as Virus Reservoirs Contributing to Mutation

Researchers obtained 1,522 nasal samples from white-tailed deer, dispersed across 83 of Ohio’s 88 counties, between November 2021 and March 2022. Over 10% of these samples tested positive for SARS-CoV-2, with at least one positive case appearing in 59% of the surveyed counties.

Genomic Insights and Observations

Genomic sequencing revealed at least 30 instances where the infection had been transmitted from humans to deer, a number that took researchers by surprise.

Andrew Bowman, Associate Professor of Veterinary Preventive Medicine at The Ohio State University and co-senior author of the study, noted, “The frequency of interspecies transmission is usually considered to be low. However, even with this relatively small sample size, we observed 30 instances of spillover between humans and animals. This suggests that the virus is traversing quite freely between the two species.”

Bowman also emphasized that evidence is accumulating to suggest the possibility of human infection originating from deer. The data implies that the transmission of SARS-CoV-2 is not exclusively in one direction.

Collective Findings and Wider Impact

The consolidated data suggests that white-tailed deer serve as a reservoir for ongoing SARS-CoV-2 mutations. There is potential for the virus circulating in deer populations to spread to other forms of wildlife and livestock.

The study was published on August 28, 2023, in the journal Nature Communications.

Prior Studies and Extended Research

Earlier studies by Bowman and his team reported the presence of SARS-CoV-2 in deer in nine locations across Ohio in December 2021. They continue to monitor the prevalence of newer variants in deer populations.

The research also extended to antibody tests, which showed that an estimated 23.5% of the state’s deer had been infected with the virus at some point.

Variant Analysis and Implications

Out of the 80 whole-genome sequences analyzed, the majority were of the highly contagious delta variant, which was dominant in the United States in early fall 2021. The sequences also included the alpha variant, which had circulated in the spring of the same year.

This genomic analysis revealed that the delta variants in deer matched the dominant lineages in humans, indicating spillover events. It also showed clustering of deer-to-deer transmission, sometimes spanning multiple counties.

Vaccination Efficacy and Evolutionary Speed in Deer

The study highlighted that existing COVID-19 vaccines appear to offer protection against severe disease in case of a reverse spillover to humans. Research on Siberian hamsters, used as animal models in SARS-CoV-2 studies, indicated that vaccinated animals displayed milder symptoms upon infection compared to their unvaccinated counterparts.

Alarmingly, the study found that both the alpha and delta variants are evolving at a faster pace in deer than in humans.

Unresolved Issues and Future Prospects

The mechanism through which the virus is transmitted from humans to deer remains elusive. Additionally, despite the large deer population in the U.S., no significant outbreaks of deer-origin strains in humans have been reported yet.

Bowman cautioned that roughly 70% of Ohio’s free-ranging deer have yet to be exposed to the virus, providing a large pool of susceptible animals through which the virus could propagate freely.

“The presence of a deer reservoir for the virus creates new variables that need to be closely monitored,” he said. “If this trend persists, it raises questions about the virus’s potential transmission to other animals, be they wildlife or domesticated. The future ramifications are still uncertain.”

The study was supported by the National Institute of Allergy and Infectious Diseases and Ohio State’s Infectious Diseases Institute. Other contributors included researchers from St. Jude Children’s Research Hospital, the University of California, Los Angeles, and various other national and international organizations.

Reference: “Accelerated evolution of SARS-CoV-2 in free-ranging white-tailed deer,” published on August 28, 2023, in Nature Communications. DOI: 10.1038/s41467-023-40706-y

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More about Accelerated COVID-19 Evolution in White-Tailed Deer

• Nature Communications Journal
• The Ohio State University Veterinary Preventive Medicine
• National Institute of Allergy and Infectious Diseases
• Ohio Department of Natural Resources
• Centers for Disease Control and Prevention on COVID-19 in Animals
• World Health Organization on COVID-19
• SARS-CoV-2 Variants of Concern
• COVID-19 Vaccine Research