CD79A and infection: While the natural infection did not induce any nasal IgG (Figure 2B), one dose of mRNA vaccine could expand the S1-specific immunoglobulin isotype in the NELF with both IgA (S/C ratio = 7.68, Figure 2A) and IgG (S/C ratio = 6.92, Figure 2B) two weeks after receiving booster (B2W).