Pneumococcal serotype matters

Abstract

The development of pneumococcal conjugate vaccines requires knowledge of specific serotypes causing disease. The implementation and universal use of 7-valent conjugate pneumococcal vaccine in children in the United States in 2000 has taught us that we need to continue to monitor the relative importance as well as the population-based incidence of disease caused by specific serotypes of Streptococcus pneumoniae. Both have shifted in surprising ways in less than a decade of conjugate vaccine use in the United States. Specific serotypes and relevant pneumococcal diseases vary by demography and geography. In this issue of The Journal, Hortal et al provide difficult-to-obtain serotype data on 387 culture-proven cases of pneumococcal pneumonia in Uruguayan children. They show that universal implementation of the 7-valent conjugate pneumococcal vaccination in Uruguay, even if 100% effective, would be expected to prevent only 60% of cases of pneumococcal pneumonia requiring hospitalization. The more we learn, the more we realize that disease due to S. pneumoniae—with at least 90 serotypes and a niche in the normal flora of the respiratory tract—will be far more difficult to prevent using protein-conjugate polysaccharide vaccines than was and still is disease due to Haemophilus influenzae type b.