title: Nonmedical exemptions to school immunization requirements: secular trends and association of state policies with pertussis incidence.
abstract: BACKGROUND
  School immunization requirements have played a major role in controlling vaccine-preventable diseases in the United States. Most states offer nonmedical exemptions to school requirements (religious or personal belief). Exemptors are at increased risk of acquiring and transmitting disease. The role of exemption policies may be especially important for pertussis, which is endemic in the United States.
  
  
  OBJECTIVE
  To determine if (1) the rates of nonmedical exemptions differ and have been increasing in states that offer only religious vs personal belief exemptions; (2) the rates of nonmedical exemptions differ and have been increasing in states that have easy vs medium and easy vs difficult processes for obtaining exemptions; and (3) pertussis incidence is associated with policies of granting personal belief exemptions, ease of obtaining exemptions, and acceptance of parental signature as sufficient proof of compliance with school immunization requirements.
  
  
  METHODS
  We analyzed 1991 through 2004 state-level rates of nonmedical exemptions at school entry and 1986 through 2004 pertussis incidence data for individuals aged 18 years or younger.
  
  
  METHODS
  State-level exemption rates and pertussis incidence.
  
  
  RESULTS
  From 2001 through 2004, states that permitted personal belief exemptions had higher nonmedical exemption rates than states that offered only religious exemptions, and states that easily granted exemptions had higher nonmedical exemption rates in 2002 through 2003 compared with states with medium and difficult exemption processes. The mean exemption rate increased an average of 6% per year, from 0.99% in 1991 to 2.54% in 2004, among states that offered personal belief exemptions. In states that easily granted exemptions, the rate increased 5% per year, from 1.26% in 1991 to 2.51% in 2004. No statistically significant change was seen in states that offered only religious exemptions or that had medium and difficult exemption processes. In multivariate analyses adjusting for demographics, easier granting of exemptions (incidence rate ratio = 1.53; 95% confidence interval, 1.10-2.14) and availability of personal belief exemptions (incidence rate ratio = 1.48; 95% confidence interval, 1.03-2.13) were associated with increased pertussis incidence.
  
  
  CONCLUSIONS
  Permitting personal belief exemptions and easily granting exemptions are associated with higher and increasing nonmedical US exemption rates. State policies granting personal belief exemptions and states that easily grant exemptions are associated with increased pertussis incidence. States should examine their exemption policies to ensure control of pertussis and other vaccine-preventable diseases.
authors.affiliation: Department of International Health, Institute for Vaccine Safety, Johns Hopkins Bloomberg School of Public Health, Baltimore, Md, USA.
authors.forename: Saad B
authors.initials: SB
authors.lastname: Omer
authors.forename: William K Y
authors.initials: WK
authors.lastname: Pan
authors.forename: Neal A
authors.initials: NA
authors.lastname: Halsey
authors.forename: Shannon
authors.initials: S
authors.lastname: Stokley
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Moulton
authors.forename: Ann Marie
authors.initials: AM
authors.lastname: Navar
authors.forename: Mathew
authors.initials: M
authors.lastname: Pierce
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Salmon
mesh_terms: D000293:Adolescent; D002648:Child; D006291:Health Policy; D006801:Humans; D010567:Pertussis Vaccine / Q000008:administration & dosage*; D012068:Religion and Medicine; D012574:Schools / Q000592:standards*; D013219:State Government; D014481:United States / Q000453:epidemiology; D014611:Vaccination / Q000592:standards* / Q000706:statistics & numerical data / Q000639:trends*; D014917:Whooping Cough / Q000453:epidemiology*
chemical_list: D010567:Pertussis Vaccine