title: Changing epidemiology of invasive pneumococcal disease among older adults in the era of pediatric pneumococcal conjugate vaccine.
abstract: BACKGROUND
  A conjugate vaccine targeting 7 pneumococcal serotypes was licensed for young children in 2000. In contrast to the 23-valent polysaccharide vaccine used in adults, the 7-valent conjugate vaccine affects pneumococcal carriage and transmission. Early after its introduction, incidence of invasive pneumococcal disease declined among older adults, a group at high risk for pneumococcal disease.
  
  
  OBJECTIVE
  To determine among adults aged 50 years or older whether incidence of invasive pneumococcal disease, disease characteristics, or the spectrum of patients acquiring these illnesses have changed over the 4 years since pneumococcal conjugate vaccine licensure.
  
  
  METHODS
  Population-based surveillance of invasive pneumococcal disease in 8 US geographic areas (total population, 18,813,000), 1998-2003.
  
  
  METHODS
  Incidence of invasive pneumococcal disease by pneumococcal serotype and other characteristics; frequency among case patients of comorbid conditions and other factors influencing mortality.
  
  
  RESULTS
  Incidence of invasive pneumococcal disease among adults aged 50 years or older declined 28% (95% confidence interval [CI], -31% to -24%), from 40.8 cases/100,000 in 1998-1999 to 29.4 in 2002-2003. Among those aged 65 years or older, the 2002-2003 rate (41.7 cases/100,000) was lower than the Healthy People 2010 goal (42 cases/100,000). Among adults aged 50 years or older, incidence of disease caused by the 7 conjugate vaccine serotypes declined 55% (95% CI, -58% to -51%) from 22.4 to 10.2 cases/100,000. In contrast, disease caused by any of the 16 serotypes only in polysaccharide vaccine did not change, and disease caused by serotypes not in either vaccine increased somewhat, from 6.0 to 6.8 cases/100,000 (13%; 95% CI, 1% to 27%). Between 1998-1999 and 2002-2003, the proportion of case-patients with human immunodeficiency virus infection increased from 1.7% (47/2737) to 5.6% (124/2231) (P<.001), and those with any comorbid condition that is an indication for pneumococcal polysaccharide vaccination increased from 62.3% (1842/2955) to 72.0% (1721/2390) (P<.001).
  
  
  CONCLUSIONS
  Our findings indicate that use of conjugate vaccine in children has substantially benefited older adults. However, persons with certain comorbid conditions may benefit less than healthier persons from the indirect effects of the new vaccine.
authors.affiliation: Minnesota Department of Health, Minneapolis 55155-2538, USA. catherine.lexau@health.state.mn.us
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Lexau
authors.forename: Ruth
authors.initials: R
authors.lastname: Lynfield
authors.forename: Richard
authors.initials: R
authors.lastname: Danila
authors.forename: Tamara
authors.initials: T
authors.lastname: Pilishvili
authors.forename: Richard
authors.initials: R
authors.lastname: Facklam
authors.forename: Monica M
authors.initials: MM
authors.lastname: Farley
authors.forename: Lee H
authors.initials: LH
authors.lastname: Harrison
authors.forename: William
authors.initials: W
authors.lastname: Schaffner
authors.forename: Arthur
authors.initials: A
authors.lastname: Reingold
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Bennett
authors.forename: James
authors.initials: J
authors.lastname: Hadler
authors.forename: Paul R
authors.initials: PR
authors.lastname: Cieslak
authors.forename: Cynthia G
authors.initials: CG
authors.lastname: Whitney
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D016015:Logistic Models; D022401:Meningococcal Vaccines / Q000008:administration & dosage*; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000503:physiopathology / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011159:Population Surveillance; D012306:Risk; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification; D016019:Survival Analysis; D014481:United States / Q000453:epidemiology; D014611:Vaccination / Q000639:trends*; D018074:Vaccines, Conjugate
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate