1342. Impact of PCV13 on Pneumococcal Colonization in Massachusetts Children
Session: Oral Abstract Session: Respiratory Infections in Children
Saturday, October 22, 2011: 2:15 PM
Room: 156ABC
Background: In March 2010, a 13-valent pneumococcal conjugate vaccine (PCV13) replaced PCV7 for use in Massachusetts.  We evaluated rates of pneumococcal colonization, by serotype and antibiotic resistance, in Massachusetts communities where serial cross-sectional surveillance has been conducted for the past decade.

Methods: Nasopharyngeal swabs were obtained from children 3 mos-<7 years of age who were seen by healthcare providers for well-child or acute illness visits in 8 Massachusetts communities.  Pneumococcal isolates were serotyped by Quellung and classified as PCV7 strains (4, 6B, 9V, 14, 18C, 19F, 23F), PCV13-included strains (1, 3, 5, 6A, 7F, 19A), or non-PCV13 strains.  Antibiotic susceptibilities were ascertained by E-test using CLSI standards.  Pneumococcal isolates obtained during the 2010-11 winter season (i.e. post-PCV13 era) were compared to isolates obtained in prior winter seasons (2006-07 and 2008-09 combined) using generalized linear mixed models to account for clustering by community.

Results: From Oct 2010 to Mar 2011, 1,058 nasopharyngeal swabs were obtained from children <6mo (7%), 6-<12mo (19%), 1-<2y (23%), 2-<5y (36%) and 5-<7y (16%). Pneumococcal colonization was similar in historical vs. 2010-11 seasons (29% vs. 32%, p=0.13), however, fewer PCV13-included strains (21% vs. 15%, p=0.038), more non-PCV13 strains (76% vs. 83%, p=0.023), and a similar proportion of PCV7- strains (3% vs. 2%, p=0.43) were present in 2010-11. Declines in colonization by PCV13-included strains occurred in young children (<6mo: 9% vs. 8%; 6-<12mo: 25% vs. 15%) while stable or increasing rates were noted in older children (1-<2y: 25% vs. 27%; 2-<5y: 29%-38%; 5-<7 y 11% vs. 12%).  Among pneumococcal isolates, the most common serotypes were 15B/C (16%), 19A (12%), 6C (9%), and 11A (7%) in 2010-11.  Non-susceptibility to penicillin (7%), ceftriaxone (11%), erythromycin (28%), clindamycin (11%), and vancomycin (1%) was not significantly different after the initiation of PCV13.

Conclusion: During the first year of PCV13 use in Massachusetts, the greatest impact on colonization is a decline PCV13-included strains in children <1y who have presumably been immunized.  Herd effects are not yet evident in older children.

Subject Category: P. Pediatric and perinatal infections

Grace M. Lee, MD, MPH1,2, Stephen I. Pelton, MD MPH3, Susan Huang, MD, MPH4, M. Maya Dutta-Linn, MPH1, Matthew Lakoma, MPH1, William P. Hanage, PhD5, Ken Kleinman, ScD1 and Jonathan A. Finkelstein, MD, MPH1,2, (1)Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, (2)Children's Hospital Boston, Boston, MA, (3)Boston Medical Center, Boston, MA, (4)UC Irvine School of Medicine, Orange, CA, (5)Harvard School of Public Health, Boston, MA


G. M. Lee, None

S. I. Pelton, Pfizer: Grant Investigator and Scientific Advisor, Honorarium for Advisory Board meetings and Research grant

S. Huang, None

M. M. Dutta-Linn, None

M. Lakoma, None

W. P. Hanage, Glaxo SmithKline: Scientific Advisor, Consulting fee

K. Kleinman, None

J. A. Finkelstein, None

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.