Pneumococcal vaccination reduces in-hospital mortality, length of stay and medical expenditure in hospitalized elderly patients.

Pneumococcal vaccination has been shown to reduce occurrence of invasive pneumococcal diseases in elderly patients. In this study, we investigated the real-world efficacy of pneumococcal vaccination implemented in elderly individuals in Japan. We reviewed the in-patient database of Juntendo University Hospital and selected elderly patients (≥65 years-old) who had received in-patient care in the general medicine department during 2014-2018. A total of 1355 patients were retrospectively enrolled and comprised of 1045 unvaccinated and 315 vaccinated elderly individuals. Prior vaccination was found associated with all-cause shorter hospital stays (adjusted RR = 0.66, 95% CI = 0.57 to 0.76) and less medical expenditure (adjusted RR = 0.76, 95% CI = 0.66 to 0.87) compared with no vaccination, as well as protection for all-cause in-hospital mortality (adjusted OR = 0.42, 95% CI = 0.22 to 0.83). The association of shorter hospital stays and less medical expenditure with vaccination was also observed in the context of pneumonia, although no altered risk in mortality was observed. In conclusion, this study is one of the first reporting real-world data after the initiation of pneumococcal vaccination program in 2014 in Japan. The national PPV23 vaccination program contributed to the reduction of all-cause in-patient days, mortality, and medical expenses in the elderly aged ≥65 years. Further data is warranted to evaluate the contribution from influenza vaccination and protein-conjugate based pneumococcal vaccine.