Salivary antibodies induced by the seven-valent PncOMPC conjugate vaccine in the Finnish Otitis Media Vaccine Trial

We studied salivary antibodies induced by a seven-valent pneumococcal conjugate vaccine (PncCRM). Healthy Finnish children (n=115), a subcohort of the Finnish Otitis Media (FinOM) Vaccine Trial, were immunised either with the PncCRM or a control vaccine (hepatitis B) at the age of 2, 4, 6, and 12 months. Salivary IgG, IgA, IgA1, IgA2 and sIg for serotypes 6B, 14, 19F, and 23F were measured at 7 and 13 months of age, and IgG and IgA also at 4-5 years of age. The PncCRM could induce both salivary anti-Pnc polysaccharide IgG and IgA. However, by the age of 4-5 years IgA concentrations had increased in both groups and were similar. The increases in IgA concentrations were mostly of IgA1 subclass. The difference between the PncCRM and the control group was more notable for serotypes 6B, 14 and 23F than for serotype 19F. We could not find evidence for the development of mucosal immunologic memory after vaccination with the PncCRM.