Affluence as a predictor of vaccine refusal and underimmunization in California private kindergartens

Abstract

Background

Non-medical vaccine exemption rates in California private schools far exceed those of public schools, but little is known about specific factors which may be associated with high exemption rates in private schools.

Methods

The percent of personal-belief exemptions (PBEs) among California public and private kindergartens were computed for 2000–2001 to 2014–2015 academic years. For the 2014–2015 academic year, a random sample of private schools was selected to investigate associations between kindergarten characteristics (tuition amount, religious affiliation) and vaccine profile (non-medical vaccine exemptions, vaccine coverage).

Results

The proportion of private kindergartens reporting 5% or more children with PBEs increased from 9% (2000–2001) to 34% (2013–2014), followed by a small decrease in 2014–2015 (31%). Overall, 93.7% (565/605) of kindergartens sampled in 2014–2015 had data available. Very high PBE levels (>20%) were seen among secular and non-Catholic, Christian kindergartens but not Roman Catholic, Jewish or Islamic kindergartens. However, the majority of schools at all tuition levels had fewer than 5% of children with a PBE. Kindergartens with an annual tuition of $10,000 or more were over twice as likely to have 20% or more children with PBEs than kindergartens with a lower tuition (p < .01). Additionally, the conditional admission proportions for kindergartens with tuitions of $10,000 or more were 39% compared to 22% for less expensive kindergartens (p < .01). Only about half of all private kindergartens had 95% coverage of the MMR (49%) and pertussis-containing vaccines (51%).

Conclusions

School-entry vaccination requirements are critical to preventing outbreaks of vaccine preventable diseases in the US. Nonmedical exemptions increased between the 2000–2001 and 2014–2015 academic years and appear to be associated with affluence, raising social justice concerns.

Introduction

Vaccines save lives and prevent substantial disability [1]. Central to maintaining effective vaccination coverage in the United States have been state laws requiring school age children attending public, and in most states private, schools to be vaccinated [2]. However, variations in state mandates and school enforcement have created disparities in vaccination coverage. As of October 2015, all states allow exemptions to school immunization requirements for medical contraindications, 48 states allow religious exemptions, and 20 states allow philosophical or personal belief exemptions (PBEs) [3]. On January 1, 2016, California will join West Virginia and Mississippi as the three states that only permit medical exemptions [4], [5]. Evidence is accumulating that states with less stringent requirements for granting exemptions tend to experience a resurgence of vaccine-preventable diseases [6], [7], [8].

Children in US private schools are more likely to have received an exemption to one or more required immunizations, and exemption rates in private schools are increasing [9], [10], [11], [12], [13]. However, the complex matrix of factors driving vaccine exemptions among private school enrollees is difficult to quantify. Families send their children to private schools for reasons that include religious beliefs, improved quality of education (e.g., smaller student:teacher ratio), and desire for a more highly controlled environment (e.g., curriculum content, school community) [14]. While religious beliefs may play a role in the vaccination decision for some faith communities, no major religion officially opposes vaccination [15]. Some faith groups have been consistently reluctant to vaccinate, however, a recent study suggests that the primary concerns contributing to under-vaccination are more closely aligned with concerns about adverse effects than faith beliefs [16]. Therefore, it is unclear whether the increasing non-medical exemption rates in private schools are motivated by religious beliefs or other potentially modifiable factors.

Affluence has also been associated with vaccine exemptions. Private schools are costly compared to free public education, and families who enroll their children in private schools, particularly those without a religious affiliation, tend to have higher incomes [17]. Thus, it is possible that the key driver of nonmedical exemptions in private schools is related to socioeconomic status (SES) rather than religious beliefs. Indeed, prior research has found parents with a college education or higher SES were more reluctant to adhere to the recommended vaccine schedule [18].

Unfortunately, census data is not available for private schools due to the geographically scattered residences of students and thus undefined catchment areas. Furthermore, private schools generally do not share matriculated families’ financial information. However, annual tuition costs are often available, and may serve as an indirect indicator of the average family's SES.

To begin describing the relationships between religion, affluence and nonmedical exemptions in private schools, we assessed whether any associations exist between (1) school type and PBEs, and (2) tuition and PBEs. We hypothesized that schools with higher tuitions would be more likely to report a greater percent of non-medical exemptions. Understanding what motivates non-medical exemptions will inform efforts to address vaccine hesitancy and inform the ongoing social fairness dialogue concerning those now bearing a disproportionate burden of establishing herd immunity.