Pneumococcal disease caused by serotype 19A: Review of the literature and implications for future vaccine development

Streptococcus pneumoniae serotype 19A is associated with all forms of pneumococcal disease and was the first reported pneumococcal serotype with high-level penicillin and multidrug resistance. While the seven-valent pneumococcal conjugate vaccine (PCV7), which contains serotype 19F, has reduced rates of disease among children and adults, the incidence of disease due to nonvaccine and increasingly drug-resistant serotypes - predominantly serotype 19A - has increased. This review summarizes the published literature to analyze the factors contributing to the emergence of serotype 19A, the diseases associated with this serotype, and the importance of including this serotype in novel pneumococcal conjugate vaccines. A recently approved 13-valent vaccine includes this serotype, and is likely to significantly reduce the burden of disease due to serotype 19A.