Pneumococcal vaccine

Abstract

Streptococcus pneumoniae (pneumococcus) is an important pathogen with high morbidity and mortality worldwide. Pneumococcal vaccine is an important measure to reduce the pneumococcal disease burden. Currently, two pneumococcal vaccines are available in adults, including 23-valent pneumococcal polysaccharide vaccine (PPV23) and 13-valent pneumococcal protein-conjugate vaccine (PCV13). PCV13 consists of capsular polysaccharides derived from the 13 most common types that cause invasive diseases (serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19F, 19A, and 23F). PPV23 covers 10 additional serotypes compared to PCV13, but it does not include serotype 6A. Even though limited in the number of serotypes, PCV13 has several important advantages over PPV23: T-cell dependent superior immunogenicity, booster effect, absence of hypo-responsiveness and protective effect on pneumonia. Although PPV23 is effective to prevent 50% to 80% of invasive pneumococcal diseases, it may be ineffective for high-risk immunocompetent and immunocompromised patients. In adults, the choice of pneumococcal vaccine should be based on the severity of underlying medical conditions and local serotype distribution. Serotype distribution is quite variable temporally and geographically. Continuous sero-surveillance is essential for the establishment of optimal vaccination strategy. © Korean Medical Association.