Citation

Serum immunoglobulin (Ig) G antibody titer against the vaccine strains of _S. pneumoniae_ was similar between the PCV13 systemic immunization group and PC IN immunization group, while the serum IgG antibody titer against PC was significantly higher in the PC IN immunization group. PC-specific IgA antibody titer in the nasal lavage and PC-specific IgA-producing cell number in the nasal mucosa were also significantly higher in the PC IN immunization group. Induction of PC-specific IgA in the PC IN immunization group enhanced the clearance of bacteria from the middle ear.