title: MMR vaccination status of children exempted from school-entry immunization mandates.
abstract: BACKGROUND
  Child immunizations are one of the most successful public health interventions of the past century. Still, parental vaccine hesitancy is widespread and increasing. One manifestation of this are rising rates of nonmedical or "personal beliefs" exemptions (PBEs) from school-entry immunization mandates. Exemptions have been shown to be associated with increased risk of disease outbreak, but the strength of this association depends critically on the true vaccination status of exempted children, which has not been assessed.
  
  
  OBJECTIVE
  To estimate the true measles-mumps-rubella (MMR) vaccination status of children with PBEs.
  
  
  METHODS
  We use administrative data collected by the California Department of Public Health in 2009 and imputation to estimate the MMR vaccination status of children with PBEs under varying scenarios.
  
  
  RESULTS
  Results from 2009 surveillance data indicate MMR1/MMR2 coverage of 18-47% among children with PBEs at typical schools and 11-34% among children with PBEs at schools with high PBE rates. Imputation scenarios point to much higher coverage (64-92% for MMR1 and 25-58% for MMR2 at typical schools; 49-90% for MMR1 and 16-63% for MMR2 at high PBE schools) but still below levels needed to maintain herd immunity against measles.
  
  
  CONCLUSIONS
  These coverage estimates suggest that prior analyses of the relative risk of measles associated with vaccine refusal underestimate that risk by an order of magnitude of 2-10 times.
authors.affiliation: Department of Family and Community Health, School of Nursing, University of Pennsylvania, 416 Fagin Hall, 418 Curie Boulevard, Philadelphia, PA 19104, USA. Electronic address: abutt@nursing.upenn.edu.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Buttenheim
authors.affiliation: Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, 714 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104-6021, USA. Electronic address: k.seth1993@gmail.com.
authors.forename: Karthik
authors.initials: K
authors.lastname: Sethuraman
authors.affiliation: Global Health and Epidemiology, Rollins School of Public Health, Emory University, Claudia N Rollins Bldg 7017, 1518 Clifton Rd, Atlanta, GA 30322, USA. Electronic address: somer@emory.edu.
authors.forename: Saad B
authors.initials: SB
authors.lastname: Omer
authors.affiliation: Department of Family and Community Health, School of Nursing, University of Pennsylvania, 416 Fagin Hall, 418 Curie Boulevard, Philadelphia, PA 19104, USA. Electronic address: alhanlon@nursing.upenn.edu.
authors.forename: Alexandra L
authors.initials: AL
authors.lastname: Hanlon
authors.affiliation: Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, 714 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104-6021, USA. Electronic address: mzlevy@mail.med.upenn.edu.
authors.forename: Michael Z
authors.initials: MZ
authors.lastname: Levy
authors.affiliation: International Health, Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolfe Street Room W5035, Baltimore, MD 21205, USA. Electronic address: dsalmon@jhsph.edu.
authors.forename: Daniel
authors.initials: D
authors.lastname: Salmon
mesh_terms: D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007114:Immunization / Q000706:statistics & numerical data*; D007223:Infant; D008457:Measles / Q000453:epidemiology* / Q000517:prevention & control*; D022542:Measles-Mumps-Rubella Vaccine / Q000008:administration & dosage*; D018570:Risk Assessment; D012574:Schools; D013334:Students
chemical_list: D022542:Measles-Mumps-Rubella Vaccine
keywords: Immunization; Imputation; Measles; Measles mumps rubella vaccine; Primary schools; Vaccination