A new scientific report confirms that cats and dogs can be infected by the novel coronavirus, and that neither animal is likely to get sick. Cats, however, do develop a strong, protective immune response, which may make them worth studying when it comes to human vaccines.

There is still no evidence to suggest that pets have passed the virus to humans, although cats do shed the virus and infect other cats.

Infected dogs in the new study didn’t produce the virus in their upper respiratory tracts and didn’t shed it at all, although some other studies have found different results. Neither the cats nor the dogs in the study showed any illness.

The authors of the report in the Proceedings of the National Academy of Sciences published Tuesday point to real world transmission to emphasize why pets are not a significant concern for human infection. Angela M. Bosco-Lauth and other researchers at Colorado State University’s College of Veterinary Medicine and Biomedical Sciences note while millions of humans have been infected with the virus worldwide and 1 million have died, there are only a handful of reports of pets that have become infected naturally.

If cats can shed the virus, why aren’t they infecting people, which is a theoretical possibility? One reason is that the number of humans who have contracted the virus is so large, and they are the ones giving it to cats. Another possible reason is that infection in everyday life is very different from infection in the lab.

In the new experimental work, scientists inserted pipettes in the nasal cavities of cats and dogs to give them the virus. The animals received anesthesia before the procedure, but the point is that this doesn’t happen in most homes. Later, other cats were put into close contact with the infected cats, who were shedding the virus.

The infected cats that showed immunity, Bosco-Lauth said, were animals that were infected by contact with other cats. And, she said the immune response was stronger than in some other laboratory animals, although how long that protection might last is completely unknown.

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