Cats provide reservoir for COVID-19, study finds

Domestic cats may be providing a reservoir for the novel coronavirus, according to a new study that suggests close to 350,000 cats in the United Kingdom have been infected with COVID-19 so far during the pandemic.

Researchers at the University of Glasgow analyzed swabs taken from 2,309 cats that had routine checkups at veterinarians in the UK between April 2020 and February this year.

The study, which was published in the preprint server bioRxiv and that has not been peer-reviewed, found that 3.2 percent of the animals tested positive for COVID-19 antibodies.

There are an estimated 10.9 million pet cats in the UK, according to a report from the People's Dispensary for Sick Animals, and if the rate of infection from the study is consistent across the population, around 348,000 cats may have contracted the virus.

Glasgow researchers said that the findings justify further research into the impact of COVID-19 on feline health. There have also been documented cases of cats transmitting COVID-19 to humans, suggesting that the animals could provide a reservoir for the virus and its variants.

"Recent evidence confirming cat-to-human COVID-19 transmission has highlighted the importance of monitoring infection in domestic cats," said the authors of the study, led by Grace Tyson, a virologist at the University of Glasgow Centre for Virus Research.

"Although the effects of COVID-19 infection on feline health are poorly characterized, cats have close contact with humans, and with both domesticated and wild animals. Accordingly, they could act as a reservoir of infection, an intermediate host, and a source of novel variants."

COVID-19 is thought to be a zoonotic disease, meaning it arose in non-human species before taking hold in the human population. The lack of coordinated international response at the start of the pandemic prompted numerous scientists to call for increased surveillance of pathogens in wild and domestic species that have the potential to infect humans.

Researchers argue that future outbreaks can be contained far more efficiently if they are discovered soon after the so-called zoonotic jump, the period in time when the disease makes the leap from animal to human.

"We need a whole army coming out ready to deal with the question of how the natural world and humanity can fit together in a way that does not have to involve infectious disease emergencies," said David Quammen, a science writer who has written several books on zoonotic viruses including Spillover, but who was not involved in the research. "Disease surveillance is crucial. And that means having eyes and ears on the ground."

Several animal species are known to be susceptible to the novel coronavirus, including dogs, cats, ferrets, hamsters, rhesus monkeys, rabbits, and fruit bats.

A research team, also from the Glasgow Centre for Virus Research, confirmed cases of human-to-cat COVID-19 transmission in 2020. The first recorded event of cat-to-human infection occurred in a veterinary clinic in Thailand this summer, though this form of transmission is thought to be rare.