Monovalent vaccination with inactivated SARS-CoV-2 BA.5 protects hamsters against Omicron but not non-Omicron variants

We compared the protective effects of inactivated SARS-CoV-2 vaccines derived from the ancestral and the currently circulating BA.5.2 strains against infection with multiple variants in Syrian golden hamsters. Vaccination with BA.5.2 effectively protected against infection with the Omicron subvariants including XBB.1, but not the Alpha or Delta variant. In contrast, hamsters vaccinated with the ancestral strain demonstrated decent neutralization activity against both the Omicron and non-Omicron variants. Our findings might instruct future design and formulation of SARS-CoV-2 vaccines.

Automated summary

In this study, the protective effects of inactivated SARS-CoV-2 vaccines derived from different strains against multiple variants in Syrian golden hamsters were compared. Vaccination with the currently circulating BA.5.2 strain effectively protected against Omicron subvariants, but not Alpha or Delta variant. In contrast, vaccination with the ancestral strain demonstrated decent neutralization activity against both Omicron and non-Omicron variants. These findings can provide guidance for the future design of SARS-CoV-2 vaccines.