662. Invasive pneumococcal disease in Massachusetts children following introduction of PCV13
Session: Poster Abstract Session: Pneumococcal Vaccines
Friday, October 21, 2011
Room: Poster Hall B1

A second generation 13 valent pneumococcal conjugate vaccine (PCV13) replaced PCV7 in the childhood immunization schedule in the USA beginning in April 2010.  Recommendations included a 3 dose primary series with booster, replacement of remaining doses of PCV7 with PCV13 and a catch-up dose for children >14 months of age.


Cases of invasive pneumococcal disease (IPD) in children < 5 years of age were detected through an enhanced surveillance system in MA in place since 2001.  All cases in children < 18 years of age and Streptococcus pneumoniae (SP) isolates, when available, are submitted to MDPH and parents/physicians are interviewed for confirmation of demographic and clinical data including vaccine history.  All available isolates are confirmed as SP, serotyped by Quellung reaction.


Fifty four cases of IPD have been identified in MA children < 5 years of age between 4.1.2010 and 3.31.2011 to date. Six (11.1%) were in infants less than 6 months; 15 (27.8%) in children between 6 and 12 months; 13 (24.1%) in toddlers 12 to 24 months and 20 (37.0%) in children between 2 and 5 years of age.  Isolates from 52 (96.3%) were available for serotyping; vaccine serotypes were identified in 31(59.6%) cases [serotype 3 (2 cases), 7F (8 cases), 18C (1 case) and 19A (20 cases)]. The incidence of IPD in the most recent year, (4.1.2010-3.31.2011) declined to 14/105 children < 5 yrs (95% CI 10.3-17.7) from a mean of 20.2/105 (95% CI 15.7-24.6) in the 8 prior years (4.1.2002-3.31.2010). The proportion of disease due to PCV13 serotypes declined to 59.2% from 66.7%, however this difference was not statistically significant (p=0.3). Among 31 cases due to PCV13 serotypes, 5 children had received no PCV (7 or 13), 14 were eligible for catch-up but had not been immunized with PCV13 and 3 cases were potential vaccine failures (2 doses of PCV13 for cases in children < 12 months and 1 dose for cases > 12 months).


A decline in incidence of IPD was observed in MA children in the first year after introduction of PCV13, yet the vaccine serotypes continue to cause ~60% of cases.  Most IPD due to PCV13 serotypes occurred in children > 12 months who had not received PCV13 or children < 12 months who had not as yet had > 2 doses.

Subject Category: I. Adult and Pediatric Vaccines

Inci Yildirim, MD MSc1, Katherine Hsu, MD, MPH2, Abbie Stevenson, BS1 and Stephen I. Pelton, MD MPH1, (1)Pediatric Infectious Diseases, Boston University BMC, Boston, MA, (2)Boston Univ Med Ctr, Boston, MA


I. Yildirim, None

K. Hsu, Pfizer: Grant Investigator, Research grant

A. Stevenson, None

S. I. Pelton, Pfizer: Scientific Advisor, Research grant

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.