title: Pertussis vaccination and the risk of respiratory syncytial virus-associated hospitalization.
abstract: BACKGROUND
  Animal data suggest an association between recent vaccination with a pertussis-containing vaccine and increased severity of respiratory syncytial virus (RSV) infection. We sought to determine whether such an association exists in humans by studying a population-based cohort of young children.
  
  
  METHODS
  We performed a nested case-control study of 280 children younger than 24 months of age hospitalized with RSV infection in Olmsted County, MN from January 1990 to December 1999. Controls (2 per case) consisted of nonhospitalized residents of Olmsted County matched to cases by date of birth and sex. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for the odds of hospitalization for RSV infection among subjects with a recent pertussis-containing vaccination in proximity to the cases' date of hospitalization relative to the odds among subjects with no vaccination.
  
  
  RESULTS
  The OR for receipt of a pertussis-containing vaccine within 0 to 6 days of a case's hospitalization for RSV disease was 0.8 (95% CI 0.4-1.8). For the time intervals 7-13, 14-20 and > or =21 days, the OR were 1.3 (95% CI 0.5-3.0), 1.3 (95% CI 0.5-3.2) and 0.7 (95% CI 0.3-1.5), respectively. Adjusting for vaccine delay and for risk status did not alter the findings. The median interval between the most recent pertussis-containing vaccine and the case's date of hospitalization was 40 days for cases and 42.5 days for controls (P = 0.69). Among the RSV cases, pertussis vaccination in the month preceding hospitalization was not a risk factor for oxygen requirement (P = 0.82), intensive care unit admission (P = 0.46) or need for mechanical ventilation (P = 0.28).
  
  
  CONCLUSIONS
  In our study, recent immunization with a pertussis-containing vaccine was not a risk factor for hospitalization for RSV infection. In addition, among children hospitalized with RSV infection, recent pertussis immunization was not associated with a more severe clinical course.
authors.affiliation: Department of Pediatric and Adolescent Medicine, Mayo Vaccine Research Group, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Boyce
authors.forename: Amy L
authors.initials: AL
authors.lastname: Weaver
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: St Sauver
authors.forename: Astrid E
authors.initials: AE
authors.lastname: Woodward-Lee
authors.forename: Judy K
authors.initials: JK
authors.lastname: Stancl
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Park
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Jacobsen
authors.forename: Robert M
authors.initials: RM
authors.lastname: Jacobson
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Poland
mesh_terms: D016022:Case-Control Studies; D006760:Hospitalization; D006801:Humans; D007223:Infant; D010567:Pertussis Vaccine / Q000009:adverse effects*; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000503:physiopathology*; D012307:Risk Factors
chemical_list: D010567:Pertussis Vaccine