title: Measles-containing vaccines and febrile seizures in children age 4 to 6 years.
abstract: BACKGROUND
  In the United States, children receive 2 doses of measles-mumps-rubella vaccine (MMR) and varicella vaccine (V), the first between ages 1 to 2 years and the second between ages 4 to 6 years. Among 1- to 2-year-olds, the risk of febrile seizures 7 to 10 days after MMRV is double that after separate MMR + V. Whether MMRV or MMR + V affects risk for febrile seizure risk among 4- to 6-year-olds has not been reported.
  
  
  METHODS
  Among 4- to 6-year-old Vaccine Safety Datalink members, we identified seizures in the emergency department and hospital from 2000 to 2008 and outpatient visits for fever from 2006 to 2008 during days 7 to 10 and 0 to 42 after MMRV and MMR + V. Incorporating medical record reviews, we assessed seizure risk after MMRV and MMR + V.
  
  
  RESULTS
  From 2006 through 2008, 86 750 children received MMRV; from 2000 through 2008, 67 438 received same-day MMR + V. Seizures were rare throughout days 0 to 42 without peaking during days 7 to 10. There was 1 febrile seizure 7 to 10 days after MMRV and 0 after MMR + V. Febrile seizure risk was 1 per 86 750 MMRV doses (95% confidence interval, 1 per 3 426 441, 1 per 15 570) and 0 per 67 438 MMR + V doses (1 per 18 282).
  
  
  CONCLUSIONS
  This study provides reassurance that MMRV and MMR + V were not associated with increased risk of febrile seizures among 4- to 6-year-olds. We can rule out with 95% confidence a risk greater than 1 febrile seizure per 15 500 MMRV doses and 1 per 18 000 MMR + V doses.
authors.affiliation: Kaiser Permanente Vaccine Study Center, Oakland, CA 94612, USA. Nicola.Klein@kp.org
authors.forename: Nicola P
authors.initials: NP
authors.lastname: Klein
authors.forename: Edwin
authors.initials: E
authors.lastname: Lewis
authors.forename: Roger
authors.initials: R
authors.lastname: Baxter
authors.forename: Eric
authors.initials: E
authors.lastname: Weintraub
authors.forename: Jason
authors.initials: J
authors.lastname: Glanz
authors.forename: Allison
authors.initials: A
authors.lastname: Naleway
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Jackson
authors.forename: James
authors.initials: J
authors.lastname: Nordin
authors.forename: Tracy
authors.initials: T
authors.lastname: Lieu
authors.forename: Edward A
authors.initials: EA
authors.lastname: Belongia
authors.forename: Bruce
authors.initials: B
authors.lastname: Fireman
mesh_terms: D019433:Chickenpox Vaccine / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D064420:Drug-Related Side Effects and Adverse Reactions; D006801:Humans; D007117:Immunization, Secondary / Q000009:adverse effects; D007223:Infant; D022542:Measles-Mumps-Rubella Vaccine / Q000009:adverse effects*; D012306:Risk; D003294:Seizures, Febrile / Q000139:chemically induced*; D014481:United States; D017778:Vaccines, Combined
chemical_list: D019433:Chickenpox Vaccine; D022542:Measles-Mumps-Rubella Vaccine; D017778:Vaccines, Combined; C050102:measles, mumps, rubella, varicella vaccine