Study Links Conscientious Vaccine Exemptions in Texas with Certain Demographics

A new study identified demographics that characterize a higher risk of conscientious vaccination exemptions (CVEs) for children in Texas.¹

The paper, which was published in PLoS Medicine, highlights high-risk indicators associated with lower vaccination rates, which could further inform targeted interventions aimed at combatting disease emergence in certain areas.

In previous studies, findings have suggested that vaccine hesitancy is positively correlated with both the educational level of the population and the proportion of the population that self-reports as ethnically white, the study researchers wrote.  

For the study, the researchers analyzed publicly available reports of the number of CVEs for 318 private, 818 public, and 60 charter school systems in Texas from the 2012 to 2013 through 2017 to 2018 school years. Because of the state’s recent population growth and declining vaccination percentages, there is a clear risk for outbreaks of vaccine-preventable diseases, although the determinants of risk are largely unknown.

“This research aims to provide actionable insight for policy makers into trends in vaccine exemptions across Texas at a granular scale,” the researchers wrote in the study.

The study looked at rural, suburban, and urban communities within each area. According to the findings, suburban and higher-income urban communities were more likely to have high vaccination exemption rates than rural counties. Among the cities included, Austin, Dallas-Fort Worth, and Houston had the highest risk of vaccine opt-outs. Moreover, areas with higher percentages of young children, ethnically white individuals, and those with a bachelor’s degree were more likely to have higher vaccination exemption rates.

Conversely, the data showed that counties with lower median income and a higher percentage of individuals who spoke a non-English language at home were more likely to have a lower vaccine opt-out rate.

The researchers were able to identify potential pockets of outbreak risks by tracking the number of individual schools and districts above the 3% exemption rate, which is the threshold for high risk.

“This study allows us to detect potential hot spots at a finer geographic scale,” study author Lauren Ancel Meyers, professor of integrative biology, said in a press release.² “The increasing numbers of exemptions are already alarming. In addition, the clustering of unvaccinated children in tight communities only amplifies the risk of an outbreak.”

According to the study, the researchers were able to use a more fine-tuned model to predict these otherwise unseen potential pockets within counties that did not cross the 3% exemption rate. For example, Travis County has a 2.3% CVE rate; however, the researchers were able to identify pockets within the county where CVEs were higher than 3%.

Overall, over the study period, median CVE percentages increased from 0.38% to 0.79%, resulting in more than 24,000 additional vaccination-exempt students. These exemptions were best explained by school system resources, the percentage of students that self-report as ethnically white, and whether the school system was in a metropolitan county. In metropolitan areas, vaccination exemptions were positively correlated with wealth and attained educational  level, the study concluded.

References:

1. Morrison M, Castro LA, Meyers LA. Conscientious vaccination exemptions in kindergarten to eighth-grade children across Texas schools from 2012 to 2018: A regression analysis. PLoS Medicine. 2020. https://doi.org/10.1371/journal.pmed.1003049

2. Demographics Linked to Choice Not to Vaccinate Children in Texas, Study Finds [news release]. The University of Texas at Austin’s website. https://news.utexas.edu/2020/03/10/demographics-linked-to-choice-not-to-vaccinate-children-in-texas-study-finds/. Accessed March 17, 2020.