This story is adapted from commentary written for National Geographic’s daily newsletter. If you’re not yet a subscriber, sign up here.

Two house cats in New York State are the first in the U.S. to test positive for the coronavirus that causes COVID-19, the Centers for Disease Control and Prevention announced on April 22. The owner of one of the cats had been diagnosed with the disease, but no one in the household of the second cat had tested positive, so it’s not yet known how the cat contracted the virus. Both cats had mild respiratory symptoms and are expected to recover.

Experts say it’s important to know that cases of pet cats acquiring coronavirus are very rare: In the world, there are only three confirmed cases of domestic cats (and two confirmed cases of dogs) getting sick. The CDC says there is no evidence at this time that the disease could spread in the opposite direction—from pets to humans.

“This is almost exclusively a human-to-human transmitted disease,” Michael San Filippo, a spokesperson for the American Veterinary Medicine Association, told NBC affiliates. “The risk to pets is very low, with only a handful of cases of the virus appearing in companion animals, and no cases of people getting sick from their pets.” (Many other human illnesses, including the common cold, do not pose threats to pets because they’re caused by species-specific viruses that are unable to infect other animals.)

One recent study, from a veterinary diagnostic lab in Maine, tested thousands of samples from dogs and cats and found no cases of the disease. While an early version of a report on a small experiment testing whether the virus could spread between cats found that indeed it can, research does not suggest that cats are a vector in spreading disease among humans.

With more than 2.6 million cases of COVID-19 globally, experts say that if pets were a significant vector, we’d know by now.

Keeping pets healthy

Many pet owners are more worried about getting their animals sick than they are about contracting illness from their pets.

To keep your pets healthy, treat them as you would any family member: If someone in your house is sick, they should isolate themselves. Make sure your pet maintains social distancing; the CDC recommends that pets not interact with anyone outside your household. When walking a dog, stay six feet away from other people (and animals) and avoid dog parks. Experts recommend washing your hands before and after interacting with a pet, just as you would with a fellow human.

The CDC and American Veterinary Medical Association do not recommend routine testing of pets at this time. (The AVMA answers pet owners’ frequently asked questions here.)

Wild animal worries

On April 5, we learned that a Malayan tiger at the Bronx Zoo tested positive for the coronavirus; on April 22, we learned that six more tigers and a lion at the Bronx Zoo have it, as well. These are the first tigers and lions known to have the virus.

Both wild and domestic cats had been known to be susceptible to feline coronavirus, a different strain, but until recently it was unknown whether they could contract SARS-CoV-2, the coronavirus that causes COVID-19.

It’s believed that the SARS-CoV-2 strain of the virus developed from a closely related coronavirus in bats. Researchers theorize that the strain evolved and jumped to an intermediate host animal, and then evolved again to infect humans.

Scientists have been working quickly to determine what other species are susceptible to infection by SARS-CoV2. Initial studies are working to identify any animal that the coronavirus could infect, whether or not it causes illness in that species. Among the species scientists are studying are cats and ferrets, both of which appear to be at least somewhat vulnerable to infection in laboratory settings (other animals studied include dogs, bats, civets, and pigs). Pangolins can carry a closely related coronavirus, but they have not been found to carry SARS-CoV-2.

Virologists caution that although the pathogen can enter the cells of some species in a lab, such infection might not occur outside of a laboratory setting. They have also determined that animals infected in a lab might not become sick. Additional testing will be needed to develop a better understanding of how this develops in animals. (Read more about how these tests are done and what we can extrapolate from them.)