LAUSR

Background: Although many guidelines in industrialized countries recommend immunization by pneumococcal vaccines, data for effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) for the patients with lung comorbidities are limited. Aim: To evaluate effectiveness of PPSV23 for the patients with lung comorbidities including in immunosuppressive state. Methods: This study is retrospective self-controlled case series design. The patients who were immunized with PPSV23 firstly in our ward during study period from April 2011 to March 2015, were eligible. The primary outcome was pneumococcal pneumonia, and the incidence rate was compared before and after PPSV23 immunization. To calculate rate ratio (RR) of pneumococcal pneumonia after immunization compared with those before immunization, Mantel-Haenszel method was used. Vaccine effectiveness (VE) was estimated as (1-RR) x 100%. Results: 130 cases (male 78%, median age 70 years) were eligible. Comorbidities were lung cancer (LCA) 56, interstitial pneumonia　（IP） 27, COPD 22, pneumonia without underlying lung disease 19, and others 6. 80% of LCA cases were immunized at the initial course of anticancer chemotherapy, and 93% of IP cases were immunized at the beginning of immunosuppressive therapy. The rates of pneumococcal pneumonia before and after immunization were 0.20 and 0.058 per 1,000 person-day, respectively. RR was 0.261 (95%CI 0.120 - 0.567). VE was 73.9% (95%CI 43.3 - 88.0). Conclusion: PPSV23 was effective and immunization should be scheduled at the early period for the patients with lung comorbidities including in immunosuppressive state.