Comparison of ELISA and RIA for measurement of pneumococcal antibodies before and after vaccination with 14-valent pneumococcal capsular polysaccharide vaccine.

Antibody responses to the 14-valent pneumococcal capsular polysaccharide vaccine in children under school age were measured by enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA). Specific IgG and IgM antibodies were usually detectable by ELISA in the prevaccination sera, and one or both of them increased as a response to the vaccination. Specific IGA antibodies were detected by ELISA in a part of the post-vaccination sera only. The frequency of the IgA responses increased with the age of the children. The correlation of the ELISA results with RIA was good (r from 0.652 to 0.812) except for type 6A (r = 0.471).