The protective effect of pneumococcal vaccination following partial splenectomy.

Weanling CD-1 male rats were subjected to 100, 75, and 50% splenectomy. One week following splenectomy, animals received either a sham immunization with 0.1 ml NS or pneumococcal immunization with 0.1 ml of a polyvalent (23) vaccine. Eight weeks following surgery, all animals received an intraperitoneal inoculation with 10(6) Streptococcus pneumoniae Type 3 organisms and were observed for mortality. Significant differences in mortality were seen between sham and immunized animals undergoing 100 or 75% splenectomy, while in the 50% group a difference was noted which did not reach statistical significance (Mantel-Cox log rank test). Patients undergoing greater than 50% splenectomy may be afforded greater protection against overwhelming pneumococcal infections by immunization with pneumococcal vaccine.