Vaccine against pneumococcal infections has led to widespread reduction in serious disease

Vaccination with the pneumococcal conjugate vaccine-7 [PCV7—a vaccine that covers 7 strains (serotypes) of Streptococcus pneumoniae] is linked to overall decreases in the rate of serious infections caused by this bacterium, such as pneumonia and meningitis, referred to as invasive pneumococcal disease (IPD), but small increases in IPD caused by serotypes of Streptococcus pneumoniae not covered by the vaccine (referred to as non-vaccine type IPD), according to a study published in PLOS Medicine this week. The results of this study, led by Daniel Feikin, Matthew Moore, and their colleagues from Johns Hopkins School of Public Health and the Centers for Disease Control and Prevention, USA, are important as they suggest rapid and sustained reductions in pneumococcal disease after vaccine introduction. The study does show that serotypes causing IPD covered by PCV-7 have been partially replaced by types not covered by PCV-7 (a phenomenon referred to as serotype replacement), which has implications...