Assessing effects of cholera vaccination in the presence of interference

Carolina Perez-Heydrich, Michael G. Hudgens, M. Elizabeth Halloran, John D. Clemens, Mohammad Ali, Michael E. Emch

Research output: Contribution to journalArticle

Abstract

Interference occurs when the treatment of one person affects the outcome of another. For example, in infectious diseases, whether one individual is vaccinated may affect whether another individual becomes infected or develops disease. Quantifying such indirect (or spillover) effects of vaccination could have important public health or policy implications. In this article we use recently developed inverse-probability weighted (IPW) estimators of treatment effects in the presence of interference to analyze an individually-randomized, placebo-controlled trial of cholera vaccination that targeted 121,982 individuals in Matlab, Bangladesh. Because these IPW estimators have not been employed previously, a simulation study was also conducted to assess the empirical behavior of the estimators in settings similar to the cholera vaccine trial. Simulation study results demonstrate the IPW estimators can yield unbiased estimates of the direct, indirect, total, and overall effects of vaccination when there is interference provided the untestable no unmeasured confounders assumption holds and the group-level propensity score model is correctly specified. Application of the IPW estimators to the cholera vaccine trial indicates the presence of interference. For example, the IPW estimates suggest on average 5.29 fewer cases of cholera per 1000 person-years (95% confidence interval 2.61, 7.96) will occur among unvaccinated individuals within neighborhoods with 60% vaccine coverage compared to neighborhoods with 32% coverage. Our analysis also demonstrates how not accounting for interference can render misleading conclusions about the public health utility of vaccination.

Original languageEnglish (US)
Pages (from-to)734-744
Number of pages11
JournalBiometrics
Volume70
Issue number3
DOIs
StatePublished - Sep 1 2014

Fingerprint

cholera
Vaccination
Cholera
Interference
vaccination
Vaccines
Vaccine
Estimator
Cholera Vaccines
Public Health
Public health
vaccines
public health
Person
Coverage
Simulation Study
Randomized Controlled Trial
Propensity Score
Public Policy
Weighted Estimates

Keywords

  • Causal inference
  • Interference
  • Inverse-probability weighted estimators
  • Spillover effect
  • Two-stage randomization
  • Vaccine

ASJC Scopus subject areas

  • Applied Mathematics
  • Statistics and Probability
  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Medicine(all)

Cite this

Perez-Heydrich, C., Hudgens, M. G., Halloran, M. E., Clemens, J. D., Ali, M., & Emch, M. E. (2014). Assessing effects of cholera vaccination in the presence of interference. Biometrics, 70(3), 734-744. https://doi.org/10.1111/biom.12184

Assessing effects of cholera vaccination in the presence of interference. / Perez-Heydrich, Carolina; Hudgens, Michael G.; Halloran, M. Elizabeth; Clemens, John D.; Ali, Mohammad; Emch, Michael E.

In: Biometrics, Vol. 70, No. 3, 01.09.2014, p. 734-744.

Research output: Contribution to journalArticle

Perez-Heydrich, C, Hudgens, MG, Halloran, ME, Clemens, JD, Ali, M & Emch, ME 2014, 'Assessing effects of cholera vaccination in the presence of interference', Biometrics, vol. 70, no. 3, pp. 734-744. https://doi.org/10.1111/biom.12184
Perez-Heydrich C, Hudgens MG, Halloran ME, Clemens JD, Ali M, Emch ME. Assessing effects of cholera vaccination in the presence of interference. Biometrics. 2014 Sep 1;70(3):734-744. https://doi.org/10.1111/biom.12184
Perez-Heydrich, Carolina ; Hudgens, Michael G. ; Halloran, M. Elizabeth ; Clemens, John D. ; Ali, Mohammad ; Emch, Michael E. / Assessing effects of cholera vaccination in the presence of interference. In: Biometrics. 2014 ; Vol. 70, No. 3. pp. 734-744.
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