Causal Inference Methods for Evaluating Vaccine Hesitancy Interventions: An Application of Instrumental Variable and Regression Discontinuity Designs to Community-Based Educational Campaigns

Deborah B. Okunola; Oladimeji Adewuyi

doi:10.56201/rjpst

📄 Download Paper

Causal Inference Methods for Evaluating Vaccine Hesitancy Interventions: An Application of Instrumental Variable and Regression Discontinuity Designs to Community-Based Educational Campaigns

Deborah B. Okunola, and Oladimeji Adewuyi

Abstract

Background: Vaccine hesitancy—defined by the World Health Organization as the delay in acceptance or refusal of vaccination despite availability—has emerged as one of the top ten threats to global health. Community-based educational campaigns are widely deployed to address hesitancy, but rigorous causal evidence of their effectiveness remains sparse. Observational evaluations are compromised by confounding from self-selection, access to care, income, and political ideology. Objective: This study demonstrates how two quasi-experimental methods—instrumental variable (IV) analysis and regression discontinuity (RD) design—can be applied to estimate the causal effect of a statewide community health worker vaccine education program on childhood vaccination uptake in a setting where randomization was not feasible. Methods: We analyzed administrative vaccination records for 68,714 children aged 12–35 months across 412 communities in a Midwestern state (2016–2021). The CHW program was allocated using a composite community risk score; communities scoring above a threshold received the intervention. We exploited this assignment mechanism using a fuzzy RD design at the eligibility threshold and, independently, used distance to the nearest CHW training center as an instrument for program participation. Outcomes included completion of the combined 7-vaccine series by 24 months and the measles-mumps-rubella first-dose rate by 15 months. Results: The RD estimate of the local average treatment effect on 7-vaccine series completion was 8.6 percentage points (95% CI: 3.4–13.8, p = 0.001). The IV estimate was 7.1 percentage points (95% CI: 2.8–11.4, p = 0.001). For MMR first-dose by 15 months, the RD estimate was 6.2 pp (95% CI: 2.1–10.3) and the IV estimate was 5.1 pp (95% CI: 1.4–8.8). Both methods produced estimates that were concordant and substantially larger than naïve OLS estimates, consistent with attenuation from confounding bias. Conclusions: Community-based CHW vaccine education programs produce meaningful increases in childhood vaccination rates. The concordance of IV and RD estimates strengthens confidence in a causal interpretation. These methods should be more widely adopted in public health program evaluation to overcome the limitations of observational comparisons.

Keywords

vaccine hesitancycausal inferenceinstrumental variablesregression discontinuitycommunity health workersimmunizationquasi-experimental design RJPST DOI: 10.56201/rjpst

References

MacDonald, N. E., & the SAGE Working Group on Vaccine Hesitancy. (2015). Vaccine hesitancy: Definition, scope, and determinants. Vaccine, 33(34), 4161–4164. World Health Organization. (2019). Ten threats to global health in 2019. Geneva: WHO. Larson, H. J., Jarrett, C., Eckersberger, E., Smith, D. M. D., & Paterson, P. (2014). Understanding vaccine hesitancy around vaccines and vaccination from a global perspective. Human Vaccines & Immunotherapeutics, 10(9), 2600–2606. Omer, S. B., Salmon, D. A., Orenstein, W. A., deHart, M. P., & Halsey, N. (2009). Vaccine refusal, mandatory immunization, and the risks of vaccine-preventable diseases. New England Journal of Medicine, 360(19), 1981–1988. Patel, M., Lee, A. D., Clemmons, N. S., et al. (2019). National update on measles cases and outbreaks—United States, January 1–October 1, 2019. MMWR Morbidity and Mortality Weekly Report, 68(40), 893–896. Angrist, J. D., & Pischke, J.-S. (2009). Mostly harmless econometrics: An empiricist’s companion. Princeton University Press. Imbens, G. W., & Lemieux, T. (2008). Regression discontinuity designs: A guide to practice. Journal of Econometrics, 142(2), 615–635. McClellan, M., McNeil, B. J., & Newhouse, J. P. (1994). Does more intensive treatment of acute myocardial infarction in the elderly reduce mortality? JAMA, 272(11), 859–866. Calonico, S., Cattaneo, M. D., & Titiunik, R. (2014). Robust nonparametric confidence intervals for regression-discontinuity designs. Econometrica, 82(6), 2295–2326. Conley, T. G., Hansen, C. B., & Rossi, P. E. (2012). Plausibly exogenous. Review of Economics and Statistics, 94(1), 260–272. Lee, D. S., & Lemieux, T. (2010). Regression discontinuity designs in economics. Journal of Economic Literature, 48(2), 281–355. Santoli, J. M., Lindley, M. C., DeSilva, M. B., et al. (2020). Effects of the COVID-19 pandemic on routine pediatric vaccine ordering and administration—United States, 2020. MMWR Morbidity and Mortality Weekly Report, 69(19), 591–593. Jarrett, C., Wilson, R., O’Leary, M., Eckersberger, E., & Larson, H. J. (2015). Strategies for addressing vaccine hesitancy—A systematic review. Vaccine, 33(34), 4180–4190. Lewin, S., Munabi-Babigumira, S., Glenton, C., et al. (2010). Lay health workers in primary and community health care for maternal and child health and the management of infectious diseases. Cochrane Database of Systematic Reviews, (3), CD004015. Montiel Olea, J. L., & Pflueger, C. (2013). A robust test for weak instruments. Journal of Business & Economic Statistics, 31(3), 358–369. McCrary, J. (2008). Manipulation of the running variable in the regression discontinuity design: A density test. Journal of Econometrics, 142(2), 698–714. Betsch, C., Schmid, P., Heinemeier, D., Korn, L., Holtmann, C., & Böhm, R. (2018). Beyond confidence: Development of a measure assessing the 5C psychological antecedents of vaccination. PLoS ONE, 13(12), e0208601. Imbens, G. W., & Kalyanaraman, K. (2012). Optimal bandwidth choice for the regression discontinuity estimator. Review of Economic Studies, 79(3), 933–959.

Causal Inference Methods for Evaluating Vaccine Hesitancy Interventions: An Application of Instrumental Variable and Regression Discontinuity Designs to Community-Based Educational Campaigns

Abstract

Keywords

References

More Articles from RESEARCH JOURNAL OF PURE SCIENCE AND TECHNOLOGY