Impact of the 7-valent pneumococcal conjugate vaccine on invasive pneumococcal disease in infants younger than 90 days in England and Wales

Abstract

Background. Streptococcus pneumoniae is an uncommon but well-recognized cause of invasive bacterial disease in young infants. This study aimed to determine the impact of the 7-valent pneumococcal conjugate vaccine (PCV7) on invasive pneumococcal disease (IPD) in infants aged <90 days in England and Wales and describe their clinical characteristics following PCV7 introduction.Methods. Trends in IPD among infants aged <90 days during 1998-1999 through 2009-2010 were analyzed using enhanced national surveillance data. Following PCV7 introduction, clinical information was also obtained for IPD cases in the birth cohorts eligible for vaccination.Results. Prior to PCV7 introduction, IPD incidence in infants aged <90 days was 13.0 (95% confidence interval [CI], 12.0-14.0) per 100 000 live births and PCV7 serotypes accounted for 44% (154/349) of serotyped isolates. PCV7 introduction resulted in 83% (95% CI, 66%-91%, P