Immune responses of splenectomized trauma patients to the 23-valent pneumococcal polysaccharide vaccine at 1 versus 7 versus 14 days after splenectomy.

OBJECTIVES: Pneumococcal polysaccharide vaccine is given after emergency splenectomy for trauma to lessen the risk of overwhelming postsplenectomy sepsis. This study was undertaken to determine optimal timing of vaccine administration as determined by serum type-specific polysaccharide antibody concentration titer and functional activity of the resulting antibodies. METHODS: Fifty-nine consecutive patients undergoing splenectomy after trauma were randomized to receive pneumococcal vaccine postoperatively at 1, 7, or 14 days. Immunoglobulin G serum antibody concentrations against serogroup 4 and serotypes 6B, 19F, and 23F were measured before vaccination and 4 weeks postvaccination. Antibody concentrations were determined by enzyme-linked immunosorbent assay, and functional antibody by opsonophagocytosis. Results were compared with a normal adult control group (n = 12). RESULTS: Postvaccination enzyme-linked immunosorbent assay immunoglobulin G antibody concentrations for all serogroups and serotypes studied were not significantly different in splenectomized patients and control subjects. Postvaccination functional antibody activity was significantly reduced in early vaccination groups (serotype 6B excepted). However, with the exception of 19F, all titers for the 14-day group approached those of the control subjects (p > 0.05). Fold-increases of opsonophagocytic titers for serogroup 4 and serotypes 6B and 19F showed progressive increases with delay in vaccination. Except for serotype 23F, the number of postsplenectomy patients with opsonophagocytic titers <64 significantly decreased with a delay in vaccination (14 days). CONCLUSIONS: Postvaccination immunoglobulin G serum antibody concentrations were not significantly different from normal control subjects regardless of the time of vaccination (1, 7, or 14 days). Although concentrations approach normal, functional antibody activity was significantly lower. Better functional antibody responses against the serogroup and serotypes studied seemed to occur with delayed (14-day) vaccination.