Pneumococcal Serotypes before and after Introduction of Conjugate Vaccines, United States, 1999–2011

Abstract

Serotyping data for pneumococci causing invasive and noninvasive disease in 2008–2009 and 2010–2011 from >43 US centers were compared with data from preconjugate vaccine (1999–2000) and postconjugate vaccine (2004–2005) periods. Prevalence of 7-valent pneumococcal conjugate vaccine serotypes decreased from 64% of invasive and 50% of noninvasive isolates in 1999–2000 to 3.8% and 4.2%, respectively, in 2010–2011. Increases in serotype 19A stopped after introduction of 13-valent pneumococcal vaccine (PCV13) in 2010. Prevalences of other predominant serotypes included in or related to PCV13 (3, 6C, 7F) also remained similar for 2008–2009 and 2010–2011. The only major serotype that increased from 2008–2009 to 2010–2011 was nonvaccine serotype 35B. These data show that introduction of the 7-valent vaccine has dramatically decreased prevalence of its serotypes and that addition of serotypes in PCV13 could provide coverage of 39% of isolates that continue to cause disease.

Keywords

• Streptococcus pneumoniae
• bacteria
• serotype
• vaccine
• conjugate vaccines
• pathogenesis