title: Risk of anaphylaxis after vaccination of children and adolescents.
abstract: OBJECTIVE
  To quantify the risk of anaphylaxis after vaccination of children and adolescents.
  
  
  METHODS
  The study population consisted of children and adolescents who were enrolled at 4 health maintenance organizations that participated in the Vaccine Safety Datalink Project. For the period 1991-1997, we identified potential cases by searching for occurrences of International Classification of Diseases, Ninth Revision (ICD-9) code 995.0 (anaphylactic shock), E948.0 through E948.9 (adverse reaction from bacterial vaccines), and E949.0 through E949.9 (adverse reaction from other vaccines and biological substances). At 1 study site, we also included a range of other allergy codes. We restricted to diagnoses on days 0 to 2 after vaccination (ICD-9 995.0) or day 0 (all other ICD-9 codes). We then reviewed the medical record to confirm the diagnosis.
  
  
  RESULTS
  We identified 5 cases of potentially vaccine-associated anaphylaxis after administration of 7 644 049 vaccine doses, for a risk of 0.65 cases/million doses (95% confidence interval: 0.21-1.53). None of the episodes resulted in death. Vaccines that were administered before the anaphylactic episodes were generally given in combination and included measles-mumps-rubella, hepatitis B, diphtheria-tetanus, diphtheria-tetanus-pertussis, Haemophilus influenzae type b, and oral polio vaccine. One case of anaphylaxis followed measles-mumps-rubella vaccine alone. At the site at which we reviewed additional allergy codes, we identified 1 case after 653 990 vaccine doses, for a risk of 1.53 cases/million doses (95% confidence interval: 0.04-8.52).
  
  
  CONCLUSIONS
  Patients and health care providers can be reassured that vaccine-associated anaphylaxis is a rare event. Nevertheless, providers should be prepared to provide immediate medical treatment should it occur.
authors.affiliation: Center for Health Studies, Group Health Cooperative, Seattle, Washington 98101-1448, USA. bohlke.k@ghc.org
authors.forename: Kari
authors.initials: K
authors.lastname: Bohlke
authors.forename: Robert L
authors.initials: RL
authors.lastname: Davis
authors.forename: S M
authors.initials: SM
authors.lastname: Marcy
authors.forename: M M
authors.initials: MM
authors.lastname: Braun
authors.forename: Frank
authors.initials: F
authors.lastname: DeStefano
authors.forename: Steven B
authors.initials: SB
authors.lastname: Black
authors.forename: John P
authors.initials: JP
authors.lastname: Mullooly
authors.forename: Robert S
authors.initials: RS
authors.lastname: Thompson
mesh_terms: D000293:Adolescent; D016907:Adverse Drug Reaction Reporting Systems / Q000706:statistics & numerical data; D000707:Anaphylaxis / Q000453:epidemiology* / Q000209:etiology; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006279:Health Maintenance Organizations / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009922:Oregon / Q000453:epidemiology; D012306:Risk; D014611:Vaccination / Q000009:adverse effects*; D014612:Vaccines / Q000009:adverse effects*; D014861:Washington / Q000453:epidemiology
chemical_list: D014612:Vaccines