title: Effect of the 2009 influenza A(H1N1) pandemic on invasive pneumococcal pneumonia.
abstract: BACKGROUND
  Because pneumococcal pneumonia was prevalent during previous influenza pandemics, we evaluated invasive pneumococcal pneumonia (IPP) rates during the 2009 influenza A(H1N1) pandemic.
  
  
  METHODS
  We identified laboratory-confirmed, influenza-associated hospitalizations and IPP cases (pneumococcus isolated from normally sterile sites with discharge diagnoses of pneumonia) using active, population-based surveillance in the United States. We compared IPP rates during peak pandemic months (April 2009-March 2010) to mean IPP rates in nonpandemic years (April 2004-March 2009) and, using Poisson models, to 2006-2008 influenza seasons.
  
  
  RESULTS
  Higher IPP rates occurred during the peak pandemic month compared to nonpandemic periods in 5-24 (IPP rate per 10 million: 48 vs 9 (95% confidence interval [CI], 5-13), 25-49 (74 vs 53 [CI, 41-65]), 50-64 (188 vs 114 [CI, 85-143]), and ≥65-year-olds (229 vs 187 [CI, 159-216]). In the models with seasonal influenza rates included, observed IPP rates during the pandemic peak were within the predicted 95% CIs, suggesting this increase was not greater than observed with seasonal influenza.
  
  
  CONCLUSIONS
  The recent influenza pandemic likely resulted in an out-of-season IPP peak among persons ≥5 years. The IPP peak's magnitude was similar to that seen during seasonal influenza epidemics.
authors.affiliation: Epidemic Intelligence Service, Centers for Disease Control and Prevention (CDC), Atlanta, GA 30333, USA. keflemi@emory.edu
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Fleming-Dutra
authors.forename: Thomas
authors.initials: T
authors.lastname: Taylor
authors.forename: Ruth
authors.initials: R
authors.lastname: Link-Gelles
authors.forename: Shikha
authors.initials: S
authors.lastname: Garg
authors.forename: Michael A
authors.initials: MA
authors.lastname: Jhung
authors.forename: Lyn
authors.initials: L
authors.lastname: Finelli
authors.forename: Seema
authors.initials: S
authors.lastname: Jain
authors.forename: David
authors.initials: D
authors.lastname: Shay
authors.forename: Sandra S
authors.initials: SS
authors.lastname: Chaves
authors.forename: Joan
authors.initials: J
authors.lastname: Baumbach
authors.forename: Emily B
authors.initials: EB
authors.lastname: Hancock
authors.forename: Bernard
authors.initials: B
authors.lastname: Beall
authors.forename: Nancy
authors.initials: N
authors.lastname: Bennett
authors.forename: Shelly
authors.initials: S
authors.lastname: Zansky
authors.forename: Susan
authors.initials: S
authors.lastname: Petit
authors.forename: Kimberly
authors.initials: K
authors.lastname: Yousey-Hindes
authors.forename: Monica M
authors.initials: MM
authors.lastname: Farley
authors.forename: Ken
authors.initials: K
authors.lastname: Gershman
authors.forename: Lee H
authors.initials: LH
authors.lastname: Harrison
authors.forename: Patricia
authors.initials: P
authors.lastname: Ryan
authors.forename: Catherine
authors.initials: C
authors.lastname: Lexau
authors.forename: Ruth
authors.initials: R
authors.lastname: Lynfield
authors.forename: Art
authors.initials: A
authors.lastname: Reingold
authors.forename: William
authors.initials: W
authors.lastname: Schaffner
authors.forename: Ann
authors.initials: A
authors.lastname: Thomas
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Moore
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D016001:Confidence Intervals; D016208:Databases, Factual; D005260:Female; D006760:Hospitalization; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000472:pathogenicity*; D007251:Influenza, Human / Q000453:epidemiology* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D058873:Pandemics; D011018:Pneumonia, Pneumococcal / Q000453:epidemiology* / Q000821:virology; D016012:Poisson Distribution; D011159:Population Surveillance; D012307:Risk Factors; D012621:Seasons; D012720:Severity of Illness Index; D013296:Streptococcus pneumoniae / Q000302:isolation & purification / Q000472:pathogenicity; D014481:United States / Q000453:epidemiology; D055815:Young Adult