Assessing effects of cholera vaccination in the presence of interference
MetadataShow full item record
© 2014, The International Biometric Society. 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.
Showing items related by title, author, creator and subject.
Effectiveness of an oral cholera vaccine in Zanzibar: Findings from a mass vaccination campaign and observational cohort studyKhatib, A.; Ali, Mohammed; von Seidlein, L.; Kim, D.; Hashim, R.; Reyburn, R.; Ley, B.; Thriemer, K.; Enwere, G.; Hutubessy, R.; Aguado, M.; Kieny, M.; Lopez, A.; Wierzba, T.; Ali, S.; Saleh, A.; Mukhopadhyay, A.; Clemens, J.; Jiddawi, M.; Deen, J. (2012)Background: Zanzibar, in east Africa, has been severely and repeatedly affected by cholera since 1978. We assessed the effectiveness of oral cholera vaccination in high-risk populations in the archipelago to estimate the ...
Safety of a killed oral cholera vaccine (Shanchol) in pregnant women in Malawi: an observational cohort studyAli, Mohammed; Nelson, A.; Luquero, F.; Azman, A.; Debes, A.; M'bang'ombe, M.; Seyama, L.; Kachale, E.; Zuze, K.; Malichi, D.; Zulu, F.; Msyamboza, K.; Kabuluzi, S.; Sack, D. (2017)© 2017 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY license Background Pregnancy increases the risk of harmful effects from cholera for both mothers and their fetuses. A killed ...
Potential for Controlling Cholera Using a Ring Vaccination Strategy: Re-analysis of Data from a Cluster-Randomized Clinical TrialAli, Mohammed; Debes, A.; Luquero, F.; Kim, D.; Park, J.; Digilio, L.; Manna, B.; Kanungo, S.; Dutta, S.; Sur, D.; Bhattacharya, S.; Sack, D. (2016)© 2016 Ali et al. Introduction: Vaccinating a buffer of individuals around a case (ring vaccination) has the potential to target those who are at highest risk of infection, reducing the number of doses needed to control ...