In late 2019, a novel coronavirus, Severe Acute Respiratory Syndrome 2 (SARS-CoV-2) emerged, resulting in a global pandemic and substantial threat to public health. Domestic cats are also susceptible to infection when in contact with infected people and, like humans, mount neutralising antibodies against the SARS-CoV-2 spike glycoprotein. In this study, we assessed the ability of sera from domestic cats to neutralise four SARS-CoV-2 pseudotypes (B.1, Alpha, Delta, and Omicron (BA.1)) to characterize feline virus neutralising antibody responses in the UK.

Pseudotype-based neutralisation assays were performed on residual serum samples collected from 806 domestic cats between 1 February 2022 and 7 July 2022. Seropositivity was confirmed using a double antigen bridging immunoassay.

In Spring-Summer 2022, feline anti-SARS-CoV-2 seroprevalence declined to 4%. Neutralising antibody titres were highest against B.1 and Delta pseudotypes and lowest against Omicron. Seropositive cats developed a neutralising antibody titre against one or more SARS-CoV-2 variants, but the degree of cross-neutralisation varied between individuals. Likelihood of seropositivity was not associated with sex, age, or pedigree of cats.

SARS-CoV-2 is circulating widely in the UK domestic cat population. The recent decline in neutralising antibody titres and the significantly weaker response against Omicron suggest that previously infected cats may be vulnerable to reinfection when exposed to newer SARS-CoV-2 variants. Adopting a One-Health strategy that involves monitoring both humans and their pets could be pivotal in helping control the COVID-19 pandemic, particularly recognising concerns about infections spilling back to humans.