SARS-CoV-2 serosurvey of healthy, privately owned cats presenting to a New York City animal hospital in the early phase of the COVID-19 pandemic (2020-2021)

Both domestic and non-domestic cats are now established to be susceptible to infection by SARS-CoV-2, the cause of the ongoing COVID-19 pandemic. While serious disease in cats may occur in some instances, the majority of infections appear to be subclinical. Differing prevalence data for SARS-CoV-2 infection of cats have been reported, and are highly context-dependent. Here, we report a retrospective serological survey of cats presented to an animal practice in New York City, located in close proximity to a large medical center that treated the first wave of COVID-19 patients in the US in the Spring of 2020. We sampled 79, mostly indoor, cats between June 2020 to May 2021, the early part of which time the community was under a strict public health “lock-down”. Using a highly sensitive and specific fluorescent bead-based multiplex assay, we found an overall prevalence of 13/79 (16%) serologically-positive animals for the study period; however, cats sampled in the Fall of 2020 had a confirmed positive prevalence of 44%. For SARS-CoV-2 seropositive cats, we performed viral neutralization test with live SARS-CoV-2 to additionally confirm presence of SARS-CoV-2 specific antibodies. Of the thirteen seropositive cats, 7/13 (54%) were also positive by virus neutralization, and 2 of seropositive cats had previously documented respiratory signs, with high neutralization titers of 1:1024 and 1:4096; overall however, there was no statistically significant association of SARS-CoV-2 seropositivity with respiratory signs, or with breed, sex or age of the animals. Follow up sampling of cats, while limited in scope, showed that positive serological titers were maintained over time. In comparison, we found an overall confirmed positive prevalence of 51% for feline coronavirus (FCoV), an endemic virus of cats, with 30% confirmed negative for FCoV. We demonstrate the impact of SARS-CoV in a defined feline population during the first wave of SARS-CoV-2 infection of humans, and suggest that human-cat transmission was substantial in our study group. Our data provide a new context for SARS-CoV-2 transmission events across species.