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

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.

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).

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%).

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.