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Address correspondence and reprint requests to: Joseph W. Thompson, MD, MPH, Arkansas Center for Health Improvement, 1401 West Capitol Avenue, Suite 300, Victory Building, Little Rock AR 72201.
Arkansas Center for Health Improvement, Little Rock, ArkansasDepartment of Pediatrics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, ArkansasDepartment of Health Policy and Management and Department of Biostatistics, College of Public Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
Department of Pediatrics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, ArkansasDepartment of Health Policy and Management and Department of Biostatistics, College of Public Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
Arkansas Center for Health Improvement, Little Rock, ArkansasDepartment of Health Policy and Management and Department of Biostatistics, College of Public Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
Department of Epidemiology and Health Policy Research, College of Medicine, University of Florida, Gainesville, FloridaDepartment of International Health, Institute for Vaccine Safety, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland.
Although incidence of vaccine-preventable diseases has decreased, states’ school immunization requirements are increasingly challenged. Subsequent to a federal court ruling affecting religious immunization exemptions to school requirements, new legislation made philosophical immunization exemptions available in Arkansas in 2003–2004. This retrospective study conducted in 2006 describes the impact of philosophical exemption legislation in Arkansas.
Arkansas Division of Health data on immunization exemptions granted were linked to Department of Education data for all school attendees (grades K through 12) during 2 school years before the legislation (2001–2002 and 2002–2003 [Years 1 and 2, respectively]) and 2 years after philosophical exemptions were available (2003–2004 and 2004–2005 [Years 3 and 4, respectively]). Changes in numbers, types, and geographic distribution of exemptions granted are described.
The total number of exemptions granted increased by 23% (529 to 651) from Year 1 to 2; by 17% (total 764) from Year 2 to 3 after philosophical exemptions were allowed; and by another 50% from Year 3 to 4 (total 1145). Nonmedical exemptions accounted for 79% of exemptions granted in Years 1 and 2, 92% in Year 3, and 95% in Year 4. Importantly, nonmedical exemptions clustered geographically, suggesting concentrated risks for vaccine-preventable diseases in Arkansas communities.
Legislation allowing philosophical exemptions from school immunization requirements was linked to increased numbers of parents claiming nonmedical exemptions, potentially causing an increase in risk for vaccine-preventable diseases. Continued education and dialogue are needed to explore the balance between individual rights and the public’s health.
Control of vaccine-preventable diseases represents a major contribution to extending life expectancy during the last century.
The supreme courts of the states and the U.S. Supreme Court also held that if states allow nonmedical exemptions, the exemption process must pass constitutional muster and not violate individuals’ constitutional rights.
While all plaintiffs requested exemptions based on religious beliefs, reasons for exemption requests varied and included statements such as “God gave us our immune systems and we must not defile the bodies with immunizations”
At the time of the suit, Arkansas allowed immunization exemptions based on both medical contraindications and belief and practice in a recognized religion that included tenets against immunization.
The federal court upheld the state’s authority to mandate immunizations. However, the state’s ability to determine whether a religion is “recognized” as a basis for exemption was ruled unconstitutional. Ironically, this eliminated a previously available option for the plaintiffs and others, leaving only medical contraindications as a basis for immunization exemption.
Subsequently, the 2003 Arkansas General Assembly passed legislation that attempted to balance individuals’ (parents’) rights to choose whether to vaccinate their children with the associated public health risks.
directed the Arkansas Department of Health (ADH, now Division of Health [DOH] in the Arkansas Department of Health and Human Services [ADHHS]) to establish a nonmedical immunization exemption process that requires annual applications by parents/guardians to request exemptions on the basis of either philosophical objections or medical contraindications. For nonmedical exemptions, the DOH continued to solicit a reason for the request—religious or philosophical—but applied consistent review criteria in granting exemptions.
While DOH tracks vaccine-preventable disease outbreaks and statewide immunization rates, and grants immunization exemptions, no school-based impact of immunization exemptions was undertaken. To evaluate the impact of these modified exemption options, investigators assessed changes in underlying risks to the public’s health from immunization exemptions by evaluating the number and geographic clustering of exempted students 2 school years before (2001–2002 and 2002–2003) and 2 years after (2003–2004 and 2004–2005) philosophical exemptions were made available.
Immunization Exemption Requirements
Since 2003 the Arkansas State Board of Health immunization exemption requirements allow either medical or nonmedical exemptions and require parental education (Table 1). Although the federal court
ruled that the state’s method of granting exemptions was unconstitutional, the “religious” category was not eliminated on the exemption request form. DOH now responds to religious exemption requests much as it does to philosophical requests. Neither the legislation nor subsequent DOH rules specifically define what constitutes valid philosophical objections. It is understood in the community that exemption requests are typically granted if required paperwork is submitted (C. Beets, Arkansas Department of Health and Human Services, personal communication, 2005). The current DOH process does require more parental educational contact than most states that allow nonmedical exemptions.
To obtain a medical exemption, only a doctor’s letter stating the medical need for the exemption is required.
for college and university students, exemptions shall be granted only by the Department of Health.
Individuals shall complete an annual application for medical, religious, and/or philosophical exemptions.
A notarized statement by the individual requesting the exemption must accompany the application.
All individuals requesting an exemption must complete an educational component developed by the Department of Health that includes information on the risks and benefits of vaccinations.
All individuals must sign an “informed consent” form provided by the Department of Health that includes the following:
(a) statement of refusal to vaccinate
(b) statement of understanding that at the discretion of the Department of Health the nonimmunized child or individual may be removed from the applicable facility during an outbreak if the child or individual is not fully vaccinated
(c) statement of understanding that the child or individual shall not return to the applicable facility until the outbreak has been resolved and the Department of Health approves the return
Note: The Arkansas Department of Health recognizes two classes of exemptions—those with a medically justifiable reason for not immunizing the child (medical exemptions) and those based on a parental objection (either religious or philosophical). Parents and guardians may apply for any of these types of exemptions (medical, religious, and philosophical).
Source: Arkansas State Board of Health. Rules and regulations pertaining to immunization requirements. Little Rock, AR: Arkansas Department of Health, 2004.
a To obtain a medical exemption, only a doctor’s letter stating the medical need for the exemption is required.
The DOH provided information on immunization exemptions for 2 school years before and after philosophical exemptions were made available. Demographic information from DOH included self-reported data on exemption request forms, such as school district, home ZIP code, age of child, and reason for exemption (medical, religious, or philosophical). Not all fields (e.g., school district) were reported for each student, and DOH does not collect or aggregate data by school or school district.
Student-level information on all school attendees was obtained for the same years from the Arkansas Department of Education (ADE). Individual data included name, date of birth, parent/guardian name, grade, age, gender, and home address and county. School-specific data for each student included the local education agency (LEA), address, county, district LEA, district county, and school year.
Data from ADE and DOH were linked to minimize missing elements and to determine where students were enrolled, that is, in daycare centers, pre-K programs, K through 12th grades, or colleges/universities. Available data were provided as Microsoft Excel (v. 2003), Microsoft Access (v. 2003), and SQL files, which were converted to Access. Before linking ADE and DOH data, DOH data were matched across multiple years using Access to fill incomplete fields. DOH data were then matched to ADE data. Primary, secondary, and tertiary linkages were performed in Access. ADE data were treated as the gold standard. Data fields where a clear linkage could not be made were coded as unknown. Linked data were used to estimate exemption rates for students in grades K through 12.
Geocoding was employed to assign residence statewide and support ascertainment of relative exemption concentrations. To map locations by school district, existing geocoding was obtained from the Arkansas Census State Data Center at the University of Arkansas at Little Rock. Calculated exemption rates were mapped using ArcGIS, v. 9 (ESRI, Redlands CA, 2004). Students with unknown locations were not included in the numerator for calculating geographic exemption rates and therefore were not represented in mappings. No patterns in missing data were discernible.
Analyses of All Exemptions
All exemption requests were categorized by the DOH as medical, religious, or philosophical. Overall exemptions were detailed by year, including those granted for students enrolled in daycare centers, pre-K programs, K through 12th grades, and colleges/universities. Proportions of students were calculated for each exemption category.
Analyses of Exemptions by Grade Groups and Public School Districts
To generate estimated exemption rates by grade group and geographic area, data were restricted to exemptions linked to ADE data. The DOH data set included not only public school students but also private school or home-schooled students who take specialized classes (e.g., calculus) at public schools, and therefore are required to abide by state immunization rules or obtain exemptions. Using the ADE data set, these students were assigned to the public school in which they were enrolled for at least one class. It was not possible to include private school and home-schooled students who did not attend public schools and who may not be immunized in the numerator for rate calculation.
Enrollment in public school grades K through 12 across the state and within school districts was stable during the 4-year timeframe, increasing <1% annually statewide and <2% over 4 years. To obtain a denominator for calculating exemption rates, the total number of private school and home schooled students reported by ADE was allocated to grade groups based on the percentage of students in public school grades because grade assignment for these students was not available from ADE.
Because data represent the entire eligible population and not a sample of students, reported comparisons of exemption rates and distributions do not include p values to denote significant differences. Overall exemption rates for all students were not calculated due to incomplete denominator identification for students in daycare centers and universities.
Exemption Granted by Type
Total exemptions numbered 529 in Year 1; 651 in Year 2; 764 in Year 3; and 1145 in Year 4. Between Years 1 and 2, the total number of exemptions granted rose by 23%. After philosophical exemptions were allowed in Year 3, total exemptions granted increased by 17% over the previous year, and by 50% more from Year 3 to 4 (Figure 1).
In Year 3, nonmedical exemptions (including religious and philosophical options) were 1.37-fold higher than nonmedical exemptions in Year 2 (139 versus 64) and 1.67-fold higher than nonmedical exemptions in Year 1 (110 versus 64), when religion was the only option for nonmedical exemptions. In Year 4, nonmedical exemptions (62) were 2.12-fold higher than in Year 2 and 2.58-fold higher than in Year 1. In Years 3 and 4, the majority of the nonmedical exemptions (58% [403 of 700] and 67% [721 of 1083], respectively) were based on philosophical rather than religious (297 and 362, respectively) reasons.
Medical exemptions constituted 21% of all exemptions in both Years 1 and 2. However, with the introduction of philosophical exemptions, the absolute number of medical exemptions dropped by more than half (from 139 in Year 2 to 64 in Year 3 and 62 in Year 4). Thus, medical exemptions accounted for only 8% of Year 3 and 5% of Year 4 exemptions.
Exemptions by Grade Group
Of the total exemptors, 39% could be categorized by grade in Year 1; 48% in Year 2; 80% in Year 3; and 74% in Year 4 (Table 2). Among students who were classified by grade, approximately 6% to 7% of exemptions were granted to kindergarten students in Years 1 and 2, but after philosophical exemptions were made available, 12% of Year 3 exemptions and 14% of Year 4 exemptions were granted to kindergartners (Table 2).
Overall exemption rates (per 1000 students) among all students classified by grade doubled after philosophical exemptions were allowed, increasing from 0.64/1000 in Year 2 to 1.26/1000 in Year 3. From Year 2 to 3, exemption rates for students in kindergarten almost quadrupled (0.49 to 1.87/1000 students) and increased by more than 6-fold from Year 2 to 4 (0.49 to 3.02/1000 students). When comparing rates in the years immediately before and after philosophical exemptions were allowed (Years 2 and 3), the increase in exemption rates was 1.8-fold for students classified in grades 1 to 5, 1.9-fold for grades 6 to 9, and 2.1-fold for grades 10 to 12 (Figure 2).
Geographic Distribution and Rates of Immunization Exemptions
Students categorized by grade were assigned to school districts for geographic analysis. Districts with the highest exemption rates were not geographically located in one area of the state. Figure 3 shows the estimated exemption rates per 1000 students in grades K through 12 for 256 public school districts in Year 4. A comparison by school district in Year 4 revealed that 60% (154 districts) reported no exemptions, while 16% (41 districts) had exemption rates of >5/1000 students.
The 10 highest estimated exemption rates for districts ranged from 7.85 to 22.97 per 1000 students in Year 4 (Table 3). It is worth noting that all exemptions granted were nonmedical in all 10 districts with the highest rates in both Years 3 and 4. A total of 113 students with nonmedical exemptions were assigned to these 10 districts in Year 4, accounting for 13% of K through 12 students who were granted exemptions.
Table 3School districts with highest immunization exemption rates (exemptions/1000 students) in 2004–2005
Not all exempted students could be classified by grade or exemption type (total number of exempted students known to be in grades K–12 was 864; and the total number of exemptions reported by the Division of Health was 1145).
a Ten highest ranking districts of 256. Students in unknown school districts are excluded from analysis.
b Overall rate is same as nonmedical rate for all top 10 school districts because no medical exemptions were claimed.
c Not all exempted students could be classified by grade or exemption type (total number of exempted students known to be in grades K–12 was 864; and the total number of exemptions reported by the Division of Health was 1145).
For example, the state’s rate among children aged 19 to 35 months was 64.2% compared with 76.1% nationally for the 4:3:1:3:3:1 series. By the time children reach school age, state law requires that parents provide proof of immunization coverage before a child enters public schools, which account for approximately 93% of Arkansas students. Before 2003, students could be exempted from the mandate only if they could document a medical contraindication or prove membership in a recognized religion with a tenet prohibiting immunization. However, public debate, court decisions, and legislative responses in Arkansas resulted in modification of school immunization requirements. In the first 2 years after philosophical exemptions were allowed, Arkansas observed an increase in the overall number of immunization exemptions granted, compared with the 2 school years immediately before the change. Arkansas data suggest that the rates of nonmedical exemptions had been increasing from Year 1 to Year 2, and consequently it is not possible to definitively determine if the increases in Years 3 and 4 comprise a trend that started before the new law or were exaggerated by the new law.
Although the actual increase in number of exemptions was modest (113 more in Year 3 than Year 2, and 381 more in Year 4 than Year 3), it may portend a continuing trend. At present the threat of an epidemic is not quantifiable, but if immunization rates continue to decline, an outbreak is more likely. For example, to avoid an epidemic of measles, an infectious disease theory
suggest that 93% to 95% immunization coverage is needed. Concentrations of children who are not immunized could result in a loss of community-level immunity and ultimately erode public health protection against vaccine-preventable illnesses.
The change in the pattern of medical exemptions granted over time—medical exemptions declined as nonmedical exemptions increased—suggests that historically, medical exemptions may have been used to avoid immunization. This possibility is supported by the decrease in medical and increase in philosophical exemptions when the latter were allowed. It is also possible that some parents whose children would have qualified for a medical exemption before the mandate claimed a philosophical exemption after modifications because it was easier than obtaining a physician’s statement. The distribution of nonmedical exemptions between religious and philosophical categories similarly supports a growing potential resistance to immunization that is not based on religious beliefs.
The finding that no medical exemptions were used in any of the 10 districts with the highest exemption rates in 2004 is noteworthy, because it suggests that the clustering of exemptions is likely a result of nonmedical reasons for refusing vaccines. A recent case–control study found that vaccine safety concerns were the primary reason parents were claiming nonmedical exemptions.
Increasing exemption rates have been associated with personal belief (philosophical) exemptions whereas states that offered only religious exemptions have not experienced an increase in exemption rates.
The data presented are consistent with this finding in that Arkansas’s permissibility of philosophical exemptions seems associated with increasing exemption rates, although it should be noted that the exemption rate in Arkansas is well under 1.0%, whereas the mean exemption rate in states that offered personal belief exemptions in 2004 was 2.5%.
Although immunization requirements are the same across school districts, variations in adherence to DOH mandates have not been investigated and may partially account for exemption clustering. Studies in other states indicate wide variability in implementation and enforcement of immunization requirements.
As with all case series, conclusions are limited in terms of inferences of causality and generalizability. Because of limited data capture in electronic format before 2001–2002, the ability to compare exemptions granted is limited to the currently presented span of 2 years before and after implementation of Act 999.
Although systems track statewide childhood vaccinations, immunization status of non-exempted or exempted groups was not validated. Importantly, philosophical exemption availability in 2003–2004 was new, and many parents who otherwise might request one may not have been cognizant of the newly authorized exemption option. Alternatively, heightened awareness of the issue emanating from the 2003 legislation may have raised concerns about safety of vaccines, resulting in more parents requesting exemptions than in previous years, but not solely because of philosophical objections. Finally, home-schooled students are not subject to state immunization requirements unless the student also attends at least one class at a public school. Therefore, the population of home-schooled students is largely not included in this study and may represent a large unvaccinated group, which is suggested by the state’s overall immunization rates. Estimated exemption rates for school districts may under-represent the actual rates for these communities.
Although DOH collections information about specific doses or type of immunization for which exemption is being requested (e.g., measles or hepatitis B), analysis of that data was beyond the scope of this study. Studies in other states indicate that the majority of exemptions are antigen-specific.
Exemptions for Arkansas students must be annually renewed. However, because of the limited information collected at the DOH level, longitudinal tracking is unavailable for individuals across years to determine whether changes in exemption numbers and types demonstrates the same individuals applying for different types of exemptions (i.e., medical to philosophical) or how many new individuals have requested exemptions.
Parental requests for exemptions from school immunization requirements appear to be increasing each year. Previous studies have documented an increased risk not only of disease acquisition by those with immunization exemptions, but also of disease transmission to those previously immunized but no longer protected.
Despite this evidence, as shown in public debate in Arkansas, parents desiring immunization exemptions perceive the risk of state-mandated immunizations to be greater than that of their children contracting vaccine-preventable diseases. Numerous scientific studies have failed to support commonly perceived adverse events after vaccination.
Despite this, parents believe they are “informed” by numerous sources, including the Internet, personal communication, and the temporal association of development of a medical condition with a vaccination.
As noted in Table 1, Arkansas uses an informed refusal model for those requesting immunization exemptions. Parents who can choose immunization exemptions must be presented with accurate and easily understood information through education programs for their decisions to be informed.
Given recent outbreaks of preventable diseases, such as the mumps outbreak that began in Iowa in December 2005 and involved at least 10 additional states as of May 2006,
an additional concern highlighted by this case study is that those who have philosophical objections based on individual rights to self-determination can adversely affect the community’s right to good public health through mandated vaccination efforts.
Advances in 20th-century health are largely attributable to widespread and systematic vaccination policies, while new vaccine developments offer promise for the 21st century. However, the medical and public health communities have not sufficiently articulated risk management strategies for typical parents. Indeed, the parental perspective may not be incorporated into public health strategies.
Parents and clinicians must share goals to optimize communication and protect individual rights while pursuing public health goals.
In conclusion, availability of a philosophical exemption has resulted in increased numbers of children at risk for disease in Arkansas. This risk, which is concentrated in various geographic areas, is not widely perceived by either the general public or clinical practitioners. Because of these focal concentrations of non-immunized children, the potential occurrence of preventable disease outbreaks is likely increased. This public health risk should be clearly communicated to healthcare providers and community members.
We wish to thank Chaitanya Katterapalli for creating the maps and Charles Beets, and Haytham Safi in the Division of Communicable Diseases/Immunization, Division of Health, Arkansas Department of Health and Human Services, for providing data.
This research was completed by the Arkansas Center for Health Improvement with support from an Arkansas Department of Health contract as a component of its legislatively required evaluation of Act 999, the Robert Wood Johnson Generalist Physician Faculty Scholars Award (039190) (JWT), and the Horace C. Cabe Foundation (RFJ, JGW).
The funding organizations played no role in the design and conduct of the study; in the collection, management, analyses, and interpretation of the data; or in the preparation, review, or approval of the manuscript for submission.
No financial conflict of interest was reported by the authors of this paper.
Centers for Disease Control and Prevention
Ten great public health achievements—United States, 1900–1999.