title: Hospitalizations associated with influenza and respiratory syncytial virus in the United States, 1993-2008.
abstract: BACKGROUND
  Age-specific comparisons of influenza and respiratory syncytial virus (RSV) hospitalization rates can inform prevention efforts, including vaccine development plans. Previous US studies have not estimated jointly the burden of these viruses using similar data sources and over many seasons.
  
  
  METHODS
  We estimated influenza and RSV hospitalizations in 5 age categories (<1, 1-4, 5-49, 50-64, and ≥65 years) with data for 13 states from 1993-1994 through 2007-2008. For each state and age group, we estimated the contribution of influenza and RSV to hospitalizations for respiratory and circulatory disease by using negative binomial regression models that incorporated weekly influenza and RSV surveillance data as covariates.
  
  
  RESULTS
  Mean rates of influenza and RSV hospitalizations were 63.5 (95% confidence interval [CI], 37.5-237) and 55.3 (95% CI, 44.4-107) per 100000 person-years, respectively. The highest hospitalization rates for influenza were among persons aged ≥65 years (309/100000; 95% CI, 186-1100) and those aged <1 year (151/100000; 95% CI, 151-660). For RSV, children aged <1 year had the highest hospitalization rate (2350/100000; 95% CI, 2220-2520) followed by those aged 1-4 years (178/100000; 95% CI, 155-230). Age-standardized annual rates per 100000 person-years varied substantially for influenza (33-100) but less for RSV (42-77).
  
  
  CONCLUSIONS
  Overall US hospitalization rates for influenza and RSV are similar; however, their age-specific burdens differ dramatically. Our estimates are consistent with those from previous studies focusing either on influenza or RSV. Our approach provides robust national comparisons of hospitalizations associated with these 2 viral respiratory pathogens by age group and over time.
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhou
authors.forename: William W
authors.initials: WW
authors.lastname: Thompson
authors.forename: Cecile G
authors.initials: CG
authors.lastname: Viboud
authors.forename: Corinne M
authors.initials: CM
authors.lastname: Ringholz
authors.forename: Po-Yung
authors.initials: PY
authors.lastname: Cheng
authors.forename: Claudia
authors.initials: C
authors.lastname: Steiner
authors.forename: Glen R
authors.initials: GR
authors.lastname: Abedi
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Anderson
authors.forename: Lynnette
authors.initials: L
authors.lastname: Brammer
authors.forename: David K
authors.initials: DK
authors.lastname: Shay
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology; D055815:Young Adult