Effectiveness of pneumococcal polysaccharide vaccine against pneumonia and cost analysis for the elderly who receive seasonal influenza vaccine in Japan.

To determine the clinical efficacy and cost-saving effect of pneumococcal polysaccharide vaccine (PPV) against community-acquired pneumonia (CAP), an open-label, randomized clinical trial was conducted involving 786 Japanese subjects older than 65 years of age receiving a routine influenza vaccine during the 2-year period. Study subjects were randomly assigned to either a PPV group (n=394) or to a non-PPV group (n=392). The incidence, admission and the medical cost for all-cause pneumonia were compared between these two groups. PPV vaccination significantly reduced the incidence of admission for all-cause pneumonia for subjects older than 75 years of age (41.5%, P=0.039) and for those who had difficulty walking (62.7%, P=0.005), but not for all study subjects older than 65 years of age (P=0.183), for the 2-year period. The Kaplan-Meier survival curves for subjects who had difficulty walking free from all-cause pneumonia demonstrated a significant difference (P=0.0146) between the two groups. PPV vaccination significantly reduced medical costs for all study subjects during the first year period (P=0.027). Our present data demonstrated that PPV was effective for all-cause pneumonia for study subjects older than 75 years of age, although the effect was not significant for all study subjects older than 65 years of age.