Primary and booster salivary antibody responses to a 7-valent pneumococcal conjugate vaccine in infants

Salivary anticapsular antibody responses to a 7-valent pneumococcal conjugate vaccine (7VPnC) were measured in healthy infants. Infants received diphtheria-tetanus-pertussis/Haemophilus influenzae type b (DTP/Hib; group 1), DTP/Hib and 7VPnC (group 2), or DTP and 7VPnC/Hib (group 3) at ages 2, 3 and 4 months. All children received 23-valent pneumococcal polysaccharide vaccine at age 13 months. Salivary IgA and IgG responses to primary immunizations were generally poor. IgA mean concentrations at age 5 months were higher in the treatment groups than in control subjects for serotype 14 only (P < .001). At age 13-14 months, there were marked increases in IgA (mean fold difference, 3.7-4.9) and Ige (mean fold difference, 4.1-11.7) levels for serotypes 4, 9V, 14, and 19F and serotypes 4, 18C, 19F, and 23F, respectively, in the treatment groups. This contrasts with low IgA (1.2 and 1.4) and IgG (1.3 and 2.2) mean fold differences for non-7VPnC serotypes 1 and 5. The results suggest that 7VPnC primes for mucosal memory responses in infants.