title: Safety of measles-containing vaccines in 1-year-old children.
abstract: OBJECTIVE
  All measles-containing vaccines are associated with several types of adverse events, including seizure, fever, and immune thrombocytopenia purpura (ITP). Because the measles-mumps-rubella-varicella (MMRV) vaccine compared with the separate measles-mumps-rubella (MMR) and varicella (MMR + V) vaccine increases a toddler's risk for febrile seizures, we investigated whether MMRV is riskier than MMR + V and whether either vaccine elevates the risk for additional safety outcomes.
  
  
  METHODS
  Study children were aged 12 to 23 months in the Vaccine Safety Datalink from 2000 to 2012. Nine study outcomes were investigated: 7 main outcomes (anaphylaxis, ITP, ataxia, arthritis, meningitis/encephalitis, acute disseminated encephalomyelitis, and Kawasaki disease), seizure, and fever. Comparing MMRV with MMR + V, relative risk was estimated by using stratified exact binomial tests. Secondary analyses examined post-MMRV or MMR + V risk versus comparison intervals; risk and comparison intervals were then contrasted for MMRV versus MMR+V.
  
  
  RESULTS
  We evaluated 123,200 MMRV and 584,987 MMR + V doses. Comparing MMRV with MMR + V, risks for the 7 main outcomes were not significantly different. Several outcomes had few or zero postvaccination events. Comparing risk versus comparison intervals, ITP risk was higher after MMRV (odds ratio [OR]: 11.3 [95% confidence interval (CI): 1.9 to 68.2]) and MMR + V (OR: 10 [95% CI: 4.5 to 22.5]) and ataxia risk was lower after both vaccines (MMRV OR: 0.8 [95% CI: 0.5 to 1]; MMR + V OR: 0.8 [95% CI: 0.7 to 0.9]). Compared with MMR + V, MMRV increased risk of seizure and fever 7 to 10 days after vaccination.
  
  
  CONCLUSIONS
  This study did not identify any new safety concerns comparing MMRV with MMR + V or after either the MMRV or the MMR + V vaccine. This study provides reassurance that these outcomes are unlikely after either vaccine.
authors.affiliation: Kaiser Permanente Vaccine Study Center, Oakland, California; nicola.klein@kp.org.
authors.forename: Nicola P
authors.initials: NP
authors.lastname: Klein
authors.affiliation: Kaiser Permanente Vaccine Study Center, Oakland, California;
authors.forename: Edwin
authors.initials: E
authors.lastname: Lewis
authors.affiliation: Kaiser Permanente Vaccine Study Center, Oakland, California;
authors.forename: Bruce
authors.initials: B
authors.lastname: Fireman
authors.affiliation: Kaiser Permanente Colorado Institute for Health Research, Denver and Department of Ambulatory Care Services, Denver Health, Denver, Colorado;
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Hambidge
authors.affiliation: The Center for Health Research, Kaiser Permanente Northwest, Portland, Oregon;
authors.forename: Allison
authors.initials: A
authors.lastname: Naleway
authors.affiliation: Group Health Cooperative and the University of Washington, Seattle, Washington;
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Nelson
authors.affiliation: Center for Clinical Epidemiology & Population Health, Marshfield Clinic Research Foundation, Marshfield, Wisconsin;
authors.forename: Edward A
authors.initials: EA
authors.lastname: Belongia
authors.affiliation: Harvard Pilgrim Health Care Institute, Boston, Massachusetts;
authors.forename: W Katherine
authors.initials: WK
authors.lastname: Yih
authors.affiliation: HealthPartners Research Foundation, Minneapolis, Minnesota;
authors.forename: James D
authors.initials: JD
authors.lastname: Nordin
authors.affiliation: Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California; and.
authors.forename: Rulin C
authors.initials: RC
authors.lastname: Hechter
authors.affiliation: Immunization Safety Office, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Eric
authors.initials: E
authors.lastname: Weintraub
authors.affiliation: Kaiser Permanente Vaccine Study Center, Oakland, California;
authors.forename: Roger
authors.initials: R
authors.lastname: Baxter
mesh_terms: D054316:Biomarkers, Pharmacological; D019433:Chickenpox Vaccine / Q000008:administration & dosage / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D022542:Measles-Mumps-Rubella Vaccine / Q000008:administration & dosage / Q000009:adverse effects*; D018570:Risk Assessment; D003294:Seizures, Febrile / Q000139:chemically induced*; D014481:United States; D017778:Vaccines, Combined / Q000008:administration & dosage / Q000009:adverse effects
chemical_list: D054316:Biomarkers, Pharmacological; D019433:Chickenpox Vaccine; D022542:Measles-Mumps-Rubella Vaccine; D017778:Vaccines, Combined; C050102:measles, mumps, rubella, varicella vaccine
keywords: measles; safety; vaccine; varicella