SARS-CoV-2 infection in vaccinated individuals induces virus-specific nasal resident CD8 and CD4 T cells of broad specificity

Rapid recognition of SARS-CoV-2-infected cells by T cells resident in the upper airway might provide an important layer of protection against COVID-19. Whether parenchymal SARS-CoV-2 vaccination or infection induce nasal resident T cells specific for distinct SARS-CoV-2 proteins is unknown. We collected T cells from the nasal secretion of COVID-19 vaccinees, who either experienced SARS-CoV-2 infection after vaccination (n=20) or not (n=15) and analyzed their phenotype, SARS-CoV-2 specificity and function. Nasal-resident IFN-γ producing SARS-CoV-2-specific CD8 and CD4 T cells were detected exclusively in vaccinees who experienced SARS-CoV-2 breakthrough infection. Importantly, the vaccine priming of Spike-specific T cells does not suppress the induction of CD8 and CD4 T cells specific for different SARS-CoV-2 proteins (i.e. NP and NSP-12) that persisted in the nasal cavity up to 3 months after infection. These data highlight the importance of viral nasal challenge in the formation of SARS-CoV-2 specific antiviral immunity at the site of primary infection and further define the immunological features of SARS-CoV-2 hybrid immunity.