Long-term immunity in convalescent Syrian hamsters provides protection against new-variant SARS-CoV-2 infection of the lower but not upper respiratory tract

COVID-19 vaccines provide high levels of protection against severe disease and hospitalization due to severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) infection. Vaccination may be less effective in preventing shedding of infectious viruses from otherwise immune patients. In this study, we describe breakthrough infections and shedding of infectious viruses in convalescent hamsters without significant replication in the lower respiratory tract following reinfection by Alpha and Delta variants despite high levels of circulating antibodies in sera. Using convalescent hamsters with long-term immunity (up to 1 year) following infection by ancestral SARS-CoV-2, we can model aspects of recurring COVID-19 in the context of preexisting immunity.

Automated summary

COVID-19 vaccines provide high levels of protection against severe disease and hospitalization, but may be less effective in preventing viral shedding in immune patients. This study used convalescent hamsters with long-term immunity to model recurring COVID-19 and found breakthrough infections and viral shedding despite no significant replication in the lower respiratory tract.