SARS-CoV-2 Vaccination in Non-Domestic Species: Insights from the Toronto Zoo
The SARS-CoV-2 pandemic has highlighted the virus’s broad host range, including susceptibility in non-domestic mammals housed in zoological collections. Vaccination has been recommended for susceptible species, particularly to protect endangered populations, but data regarding vaccine safety and efficacy in exotic animals have been scarce. A recent study conducted at the Toronto Zoo provides valuable insight into immune responses to the Zoetis® Experimental Mink Coronavirus Vaccine (Subunit), which was temporarily authorized for emergency use in North America between 2021 and 2024.
The study evaluated 24 animals across four taxonomic families — Cervidae (deer), Felidae (cats), Ursidae (bears), and Hyaenidae (hyenas). Serum samples were collected and tested using both a surrogate virus neutralization test (sVNT)and a plaque-reduction neutralization test (PRNT) to assess the development of SARS-CoV-2 neutralizing antibodies.
Most species developed measurable neutralizing titers after at least one vaccine dose. Felids and hyenas exhibited the highest neutralizing responses, peaking approximately three months after vaccination, before gradually declining between four and six months post-boost. In contrast, polar bears showed no seroconversion, highlighting the importance of species-specific responses and potentially indicating a need for tailored vaccination protocols.
The differences observed in vaccine response are likely multifactorial, reflecting species-specific immunology, age, individual health status, and the lack of standardized vaccination protocols across non-domestic species. While natural infection could not be fully ruled out in the study cohort, the results provide compelling evidence that SARS-CoV-2 vaccines can elicit protective immunity in multiple exotic species.
Importantly, the study also emphasizes the utility of competitive assays to evaluate immune responses in a broad range of species, especially when traditional reagents, such as anti-isotype antibodies, are not available. These findings offer practical guidance for veterinarians involved in zoo medicine and wildlife conservation, supporting the use of SARS-CoV-2 vaccination in susceptible species while underscoring the need for ongoing monitoring and protocol refinement.
In conclusion, the Toronto Zoo study demonstrates that SARS-CoV-2 vaccination can be immunogenic across diverse non-domestic mammals, with notable variation between species. These insights will inform future vaccination strategies in zoological collections, helping safeguard animal health and supporting conservation efforts in the face of emerging infectious diseases.
Read full study here: SARS-COV-2 Vaccination Response in Non-Domestic Species Housed at the Toronto Zoo
