Surveillance for invasive pneumococcal disease during 2000-2005 in a population of children who received 7-valent pneumococcal conjugate vaccine.
OBJECTIVE
To assess the incidence of invasive pneumococcal disease (IPD) in all children younger than 5 years of age in the Northern California Kaiser Permanente (NCKP) health care system during a 5-year surveillance period (2000-2005) after the introduction in April 2000 of routine use of 7-valent pneumococcal conjugate vaccine (PCV7).


METHODS
This was a laboratory-based surveillance study of all children younger than 5 years of age in the NCKP health care system from April 2000 to March 2005. The comparison group was all children younger than 5 years of age in the NCKP health care system from April 1996 to March 2000. Data obtained from clinical databases included microbiologic identification and susceptibility testing; serotyping of isolates; immunization records; and IPD diagnoses for inpatients and outpatients. IPD was defined as a positive culture of Streptococcus pneumoniae from a normally sterile body site.


RESULTS
For all serotypes, the mean annual incidence of IPD during the postlicensure surveillance period was 15.3 cases/100,000 person-years (10(5) p-y) compared with 62.5 cases/10(5) p-y in the prelicensure years of 1996-2000. The average incidence of IPD caused by vaccine serotypes was reduced from 50.1 cases/10(5) p-y during the prelicensure years to 4.9 cases/10(5) p-y during the postlicensure period. The average incidences of IPD caused by cross-reactive and by nonvaccine serotypes were 5.8 and 5.3 cases/10(5) p-y, respectively, during the prelicensure years and 2.5 and 6.2 cases/10(5) p-y, respectively, during the postlicensure period. Of the 131 IPD cases observed during the postlicensure surveillance period, bacteremia (50.4%) and pneumonia (31.3%) were the most common diagnoses. During the 5-year postlicensure surveillance period, only 3 subjects who were identified to be fully vaccinated for age with PCV7 (3 doses by 7 months of age or 4 doses by 18 months of age) developed vaccine-serotype IPD.


CONCLUSIONS
The incidence of IPD has significantly decreased in a large population of children after the introduction of PCV7. Vaccine-type IPD was rare in patients who received full 4-dose immunization with PCV7. There is no clear evidence of a significant increase in nonvaccine-serotype IPD. Introduction of a 4-dose infant schedule of PCV7 into this population has resulted in a marked and sustained reduction of IPD in children.
Black
Steven
S
Division of Pediatric Infectious Diseases, Stanford University School of Medicine, Stanford, CA, USA.
France
Eric K
EK
Isaacman
Daniel
D
Bracken
Laura
L
Lewis
Edwin
E
Hansen
John
J
Fireman
Bruce
B
Austrian
Robert
R
Graepel
Jay
J
Gray
Sharon
S
Klein
Nicola P
NP
D002140:California / Q000453:epidemiology; D002675:Child, Preschool; D005260:Female; D006279:Health Maintenance Organizations; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011358:Product Surveillance, Postmarketing; D018571:Sentinel Surveillance; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification
D022242:Pneumococcal Vaccines