Sustained Reductions in Invasive Pneumococcal Disease in the Era of Conjugate Vaccine

TLDR

The study compared IPD incidence in 2007 to 1998–1999 before PCV7 and evaluated serotype coverage of newer conjugate vaccines. IPD incidence was assessed over 1998–2007 using laboratory‑confirmed cases from eight active population‑based surveillance sites following 7 years of PCV7 use in US children. IPD incidence from PCV7 serotypes fell 94% while non‑PCV7 serotypes, notably 19A, rose modestly (from 0.8 to 2.7 and 6.1 to 7.9 cases/100,000), with meningitis and invasive pneumonia rates increasing but primary bacteremia unchanged, and by 2006–2007 PCV7 accounted for only 2% of cases while 13‑valent vaccine serotypes covered 63% of cases in children < 5, confirming sustained overall reductions after 7 years of PCV7 use.

Abstract

Changes in invasive pneumococcal disease (IPD) incidence were evaluated after 7 years of 7-valent pneumococcal conjugate vaccine (PCV7) use in US children.Laboratory-confirmed IPD cases were identified during 1998-2007 by 8 active population-based surveillance sites. We compared overall, age group-specific, syndrome-specific, and serotype group-specific IPD incidence in 2007 with that in 1998-1999 (before PCV7) and assessed potential serotype coverage of new conjugate vaccine formulations.Overall and PCV7-type IPD incidence declined by 45% (from 24.4 to 13.5 cases per 100,000 population) and 94% (from 15.5 to 1.0 cases per 100,000 population), respectively (P< .01 all age groups). The incidence of IPD caused by serotype 19A and other non-PCV7 types increased from 0.8 to 2.7 cases per 100,000 population and from 6.1 to 7.9 cases per 100,000 population, respectively (P< .01 for all age groups). The rates of meningitis and invasive pneumonia caused by non-PCV7 types increased for all age groups (P< .05), whereas the rates of primary bacteremia caused by these serotypes did not change. In 2006-2007, PCV7 types caused 2% of IPD cases, and the 6 additional serotypes included in an investigational 13-valent conjugate vaccine caused 63% of IPD cases among children <5 years-old.Dramatic reductions in IPD after PCV7 introduction in the United States remain evident 7 years later. IPD rates caused by serotype 19A and other non-PCV7 types have increased but remain low relative to decreases in PCV7-type IPD.