Clinical effectiveness of 23-valent pneumococcal polysaccharide vaccine against pneumonia in patients with chronic pulmonary diseases

Abstract

Background The effectiveness of the 23-valent polysaccharide pneumococcal vaccine (PPV-23) is controversial, especially among people with high-risk conditions. This study assessed the clinical effectiveness of vaccination against pneumonia among patients with chronic pulmonary diseases.Methods We conducted a population-based case-control study including 96 non-immunocompromised patients with clinical diagnosis of chronic pulmonary disease (chronic bronchitis, emphysema and/or asthma), aged 50 y or older, with radiographically confirmed pneumococcal pneumonia (19 bacteremic and 77 nonbacteremic cases) and 192 outpatient control subjects with similar chronic pulmonary diseases (matched by primary care center, age, sex and main comorbidity). Adjusted odds ratios (ORs) for vaccination were calculated using conditional logistic regression, controlling for by underlying conditions.Results Pneumococcal vaccination did not alter significantly the risk of overall pneumococcal pneumonia [adjusted OR: 0.71; 95% confidence interval (CI): 0.37–1.39]. Point estimates of vaccine effectiveness was the maximum against bacteremic pneumococcal pneumonia due to vaccine-serotypes, although neither reached statistical significance (adjusted OR: 0.51; 95% CI: 0.03–8.19). Vaccination pointed to a smaller benefit against nonbacteremic pneumococcal pneumonia (adjusted OR: 0.66; 95% CI: 0.33–1.34). Pneumococcal vaccination was associated with a non-statistically significant reduction in the risk of all pneumococcal pneumonia among persons 75 y or older (adjusted OR: 0.45; 95% CI: 0.16–1.27), but no apparent protective effect emerged among people 50–74 y (adjusted OR: 1.48; 95% CI: 0.62–3.56).Conclusions The effectiveness of the PPV-23 in preventing pneumonia among patients with chronic pulmonary disease is uncertain. Our results point to PPV-23 having little or null effect against pneumococcal pneumonia in such patients, but definitive conclusions cannot be established based on our data.