Salivary antibody responses to oral and parenteral vaccines in children.

Salivary IgA antibody to poliovirus and tetanus toxoid was measured in whole salivas of 151 children between 2 and 48 months of age from North America and from Scandinavia. Children from urban and suburban populations in the greater Boston, MA, area receive both oral poliovaccine and a parenteral injection with tetanus toxoid (TT), initially at approximately 2 months of age. Children from Göteborg, Sweden, initially receive parenteral injections of TT at 2 months of age and parenteral injections of killed polio vaccine initially at 9 to 10 months of age. Twenty-six percent of the Boston subjects who were less than 12 months old had detectable salivary IgA antibody to poliovirus after oral immunization. In contrast, within the first year after parenteral immunization with killed poliovirus, the Swedish group had detectable salivary antibody in 9% (1 of 13) of the subjects. Forty to 65% of the children in the older Boston-area age groups had positive salivary IgA antibody levels to this antigen. No differences were seen in salivary IgA antibody to TT among the three populations. By 36 months of age at least 50% of all populations had detectable salivary antibody to TT. The ratio of enzyme-linked immunosorbent assay (ELISA) activity using rabbit anti-human secretory component versus rabbit anti-human alpha chain was significantly higher in subjects less than 12 months of age compared with older groups. This suggested either that free secretory component was binding to tetanus toxoid or that secretory antibody of isotypes other than IgA was present in these youngest subjects.