Rising SARS-CoV-2 Seroprevalence and Patterns of Cross-Variant Antibody Neutralization in UK Domestic Cats

Recent evidence confirming cat-to-human SARS-CoV-2 transmission has highlighted the importance of monitoring infection in domestic cats. Although the effects of SARS-CoV-2 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. To investigate the spread of the virus in the cat population, serum samples were tested for SARS-CoV-2 antibodies by ELISA and a pseudotype-based virus neutralization assay, designed to detect exposure to variants known to be circulating in the human population. Overall seroprevalence was 3.2%, peaking at 5.3% in autumn 2021. Variant-specific neutralizing antibody responses were detected with titers waning over time. The variant-specific response in the feline population correlated with and trailed the variants circulating in the human population, indicating multiple ongoing human-to-cat spill-over events.