Phase 1 trial of a 13-valent pneumococcal conjugate vaccine in healthy adults.

In a Phase 1 study, 15 healthy subjects were randomized to receive a 13-valent pneumococcal conjugate vaccine (PCV13) and 15 to receive a 23-valent pneumococcal polysaccharide vaccine (23vPS). Antibody responses were measured immediately before and approximately one month after vaccination. Serotype-specific antibodies were measured using an enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) and an opsonophagocytic assay (OPA) for functional antibodies. PCV13 was as immunogenic or more immunogenic than 23vPS and was well tolerated.