Exposure to children as a risk factor for bacteremic pneumococcal disease: changes in the post-conjugate vaccine era.
BACKGROUND
The introduction of a pneumococcal conjugate vaccine has been associated with a shift in the serotypes responsible for bacteremic pneumococcal disease. We examined recent trends in serotypes responsible for disease and current risk factors among adults.


METHODS
Data were obtained from 48 acute care hospitals in the 5-county region surrounding Philadelphia, Pennsylvania, from October 1, 2002, through September 30, 2008, on all hospitalized adult patients with community-acquired bacteremic pneumococcal disease. Isolates were serotyped and patient characteristics were compared with data from a household survey of the adult population in the region.


RESULTS
During the study period, the annual rate of disease due to vaccine serotypes declined by 29% per year, but the rate of disease due to nonvaccine serotypes increased 13% per year, yielding an overall 7% increase in the annual rate of disease among adults. Advanced age was a risk factor for infection with nonvaccine serotypes compared with vaccine serotypes. Comparing all patients with the source population, African Americans were at increased risk of infection, and the presence of additional children in the home was associated with decreased risk of disease. Smoking, advanced age, and diabetes mellitus remained important risk factors in adults.


CONCLUSIONS
New serotypes are replacing the serotypes covered in the conjugate vaccine. While some risk factors for pneumococcal disease remain unchanged, the observation that exposure to children in the home is associated with lower risk of disease suggests that the changing epidemiology of pneumococcal disease may be altering the dominant modes of transmission in the community.
Metlay
Joshua P
JP
Department of Medicine, University of Pennsylvania School of Medicine, 712 Blockley Hall, 423 Guardian Dr, Philadelphia, PA 19104, USA. jmetlay@mail.med.upenn.edu
Lautenbach
Ebbing
E
Li
Yimei
Y
Shults
Justine
J
Edelstein
Paul H
PH
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D016001:Confidence Intervals; D018562:Disease Transmission, Infectious / Q000517:prevention & control* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010414:Pennsylvania / Q000453:epidemiology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology; D016012:Poisson Distribution; D011336:Probability; D016016:Proportional Hazards Models; D018570:Risk Assessment; D017678:Sex Distribution; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology; D055815:Young Adult
D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate