How animals are contributing to new COVID variants—and what the CDC wants you to do about it

By Jules Murtha | Fact-checked by Barbara Bekiesz
Published April 5, 2022

Key Takeaways

  • The CDC calls on public health officials to collaborate using a One Health approach to better track the evolution of COVID variants among companion animals.

  • The dawn of SARS-CoV-2 is the result of viral spillover from animals to humans—and now it's jumping between animal species, including companion animals.

  • The virus changes rapidly as it transmits from one species to the next, evolving and paving the way for new strains with repeated transmissions.

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Soon after COVID-19 first struck humans in Wuhan, China, scientists largely concluded that the virus originated in animals. Three years following its zoonotic leap, COVID-19 continues to infect a wide range of animals, and common house pets are no exception—posing a unique challenge to physicians and other medical professionals across the board.[]

To mitigate the spread of COVID-19 from positive-testing companion animals to humans, the CDC encourages healthcare professionals, veterinarians, and other public health officials to take the One Health approach by establishing an open flow of communication to create effective care plans.

The role of animals in variant selection

Let’s get back to the basics: The COVID-19 pandemic is a result of viral spillover from animals to humans. That spillover has continued to travel back to animals at increasing rates, which could have notable consequences for how the virus evolves.

According to a study published by the Proceedings of the National Academy of Sciences of the USA, repeated cross-species transmission of the virus can cause it to rapidly adapt to a new environment or host body.[] This may cause the inception of new SARS-CoV-2 strains, which can alter the virus’s pathogenicity and transmissibility.

Compounding the issue is the fact that common household animals have tested positive for the disease. Widespread transmission of SARS-CoV-2 exists among cats, mink, and deer, among other species.

Spillback events

One spillback incident involves feral cats living on a mink farm in The Netherlands. These cats were seropositive for COVID-19, likely due to exposure from the minks. Meanwhile, the farm’s domesticated cats tested seronegative.

Another noteworthy spillback event affected free-range, white-tailed deer in Michigan, Illinois, New York, and Pennsylvania. These deer exhibited a 33% seropositive rate.

A later PCR test confirmed that a white-tailed deer in Ohio also contracted the virus. Thus, the existence of domestic animal and wildlife SARS-CoV-2 reservoirs is very likely.

In addition, about 50% of households worldwide have cats and dogs, both of which can contract and pass on the virus—potentially in the form of a new variant.

The good news is that, based on the limited available data, there’s a relatively low risk of humans contracting COVID from animals. But—as we’ve witnessed in the initial transmission of COVID to humans—it’s still possible.

Take a One Health approach

While the CDC states that the primary mode of COVID-19 transmission to humans is from exposure to other infected humans, there are still important steps to take when a companion animal tests positive.[]

Similar to humans, animals can exhibit the following symptoms as a result of a COVID-19 infection: fever, coughing, shortness of breath, sneezing, nasal and ocular discharge, lethargy, vomiting, and diarrhea.

If a companion animal tests positive, the CDC recommends that state, local, and federal public health and animal health partners use the One Health approach to reduce human exposure to the infected animal.[]

One Health recognizes the interconnectedness of health between animals and humans.

This approach also factors in the health of the environment. It calls on doctors, nurses, epidemiologists, veterinarians, paraprofessionals, agricultural workers, wildlife experts, and other public officials to work together to effectively address public health issues.

To achieve this, a flow of information between public health officials and federal agencies regarding COVID-positive animals is crucial, along with developing a care plan that clarifies where the animal will receive treatment. The risk of serious illness in the animal's owner or caretaker, in addition to that person's emotional well-being upon separation from the animal, should also play a role in the decision-making process.

What this means for you

To track the evolution of the virus among animals and humans, and to determine appropriate care for infected animals, the CDC recommends that health officials implement the One Health approach. This method addresses companion animals who’ve tested positive for the virus, and prioritizes limiting human exposure to them.

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