Sustained reductions in invasive pneumococcal disease in the era of conjugate vaccine.
BACKGROUND
Changes in invasive pneumococcal disease (IPD) incidence were evaluated after 7 years of 7-valent pneumococcal conjugate vaccine (PCV7) use in US children.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Pilishvili
Tamara
T
Division of Bacterial Diseases and Centers for Disease Control and Prevention, Atlanta, Georgia, USA. tpilishvili@cdc.gov
Lexau
Catherine
C
Farley
Monica M
MM
Hadler
James
J
Harrison
Lee H
LH
Bennett
Nancy M
NM
Reingold
Arthur
A
Thomas
Ann
A
Schaffner
William
W
Craig
Allen S
AS
Smith
Philip J
PJ
Beall
Bernard W
BW
Whitney
Cynthia G
CG
Moore
Matthew R
MR
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D002648:Child; D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines; D011159:Population Surveillance; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification; D014481:United States / Q000453:epidemiology; D055815:Young Adult
D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines