Is the 23-valent pneumococcal polysaccharide vaccine useful in preventing community-acquired pneumonia?

Although bacteremic pneumococcal pneumonia is the most severe form of pneumonia, non-bacteremic forms are much more frequent. Laboratory methods for the diagnosis of nonbacteremic pneumococcal pneumonia have a low sensitivity and specificity, and therefore all-cause pneumonia has been proposed as a suitable outcome to evaluate vaccination effectiveness. This work reviews the epidemiology of community-acquired pneumonia (CAP) and evaluates the effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPV-23) in preventing CAP requiring hospitalization in people aged ≥65 years. We performed a case-control study in patients aged ≥65 years admitted through the emergency department who presented with clinical signs and symptoms compatible with pneumonia. We included 489 cases and 1,467 controls and it was obtained a vaccine efectiveness of 23.6 (0.9-41.0). Our results suggest that PPV-23 vaccination is effective and reduces hospital admissions due to pneumonia in the elderly, strengthening the rationale for vaccination programmes in this age group. Correspondence/Reprint request: Dr. Conchita Izquierdo, Directorate of Public Health. Generalitat of Catalonia. Roc Boronat 81-95, 08005 Barcelona, Spain; Department of Public Health. University of Barcelona Casanovas 143, 08036 Barcelona, Spain. E-mail: conchita.izquierdo@gencat.cat Conchita Izquierdo et al. 70