CD79A and infection: Based on our newly established nasal IgA antibody detection platform, this study revealed that 93.3% of individuals who received the live attenuated influenza virus vector-based intranasal SARS-CoV-2 vaccine tested above the dilution-adjusted LOQ three months post-vaccination, with significantly higher nasal SARS-CoV-2 WT-RBD IgA concentrations compared to asymptomatic individuals and convalescent individuals 10 months post-breakthrough infection.