Study: Variants of COVID-19 in cats followed the same timeline as the human population

Household cats acquired the same COVID-19 variants as their owners throughout the pandemic, according to new research.

The study, published in Emerging Infectious Diseases and led by the MRC-University of Glasgow Center for Virus Research (CVR)—where scientists first detected human-to-cat COVID-19 transmission in April 2021—found a retrospective association between the dominant SARS-CoV-2 variant observed in cats and the timeline of variant emergence in the human population.

The research also found that patterns of immunity to different variants in cats reflect the human pandemic, indicating multiple ongoing human-to-cat transmission events. However, it is unknown whether individual SARS-CoV-2 variants are more or less likely to be transmitted from humans to cats, or whether infected cats are more or less likely to develop clinical signs.

Grace Tyson, a Ph.D. student at the CVR and lead author of the study, said, "Our findings suggest that there has been continued human-to-cat transmissions of SARS-CoV-2. Therefore, it is important that we continue to monitor SARS-CoV-2 infections in pet cats that are in close contact with their COVID-19 positive owners, as it will be important to monitor changes in transmissibility of emerging variants in cats as well as humans."

Professor Margaret Hosie, also from the CVR, added, "We predicted that the low seroprevalence reported in cats early in the pandemic would increase as new, more transmissible variants emerged, and we are continuing to monitor cats for evidence of infection with currently circulating variants. Currently, our recommendation is that if cats regularly going outside, then they should still be allowed outdoor access if their owners have COVID-19. This decreases the risk of the cats becoming infected from their owners.

"Since human-to-cat transmission of SARS-CoV-2 occurs relatively frequently in COVID-19 positive households, the results of this study demonstrate the importance of monitoring coronavirus infections in pet cats that are in close contact with their positive owners, adopting a 'one health' strategy."

The researchers studied residual blood samples from 2,309 cats, submitted to the University of Glasgow Veterinary Diagnostic Services laboratory (VDS) between April 2020 and February 2022. The samples represented a cohort that was broadly representative of the U.K. domestic cat population, including samples from 112 of the 126 U.K. postcode areas.

Since the start of the pandemic, the World Organization for Animal Health has reported that 31 different animal species had been infected with SARS-CoV-2 by 10 March 2023.