CD79A and infection: Although the evaluation of respiratory mucosal IgA antibodies against SARS-CoV-2 was hindered by the technical difficulty in harvesting respiratory samples, experiences from live attenuated influenza vaccines suggest that the natural infection of Omicron BA.5.2 should be able to induce respiratory mucosal IgA antibodies, which are the first defense line of adaptive immunity [11,12,13].