We identified three primary mechanisms of spillovers : reduced disease transmission , social proximity and substitution of re sources within households .
We found the strongest evidence for spillovers through reduced disease transmission , particularly vaccines and mass drug administration .
In general , the proportion of a population receiving an intervention was associated with improved health .
We found evidence of publication bias for certain spillover estimates but not for total or direct effects .
Conclusions We found the strongest evidence for spillovers from vaccines and mass drug administration to control infectious disease .
There was little high quality evidence of spillovers for other interventions
Background Many interventions delivered to improve health may benefit not only direct recipients but also people in close physical or social proximity .
Our objective was to review all published literature about the spillover effects of interventions on health outcomes in low-middle income countries and to identify methods used in estimating these effects .
Assessing effects of cholera vaccination in the presence of interference.
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 implication s. In this article we use recently developed inverse-probability weighted ( IPW ) estimators of treatment effects in the presence of interference to analyze an individually-r and omized , 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 setting s 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
We identified three primary mechanisms of spillovers : reduced disease transmission , social proximity and substitution of re sources within households .
We found the strongest evidence for spillovers through reduced disease transmission , particularly vaccines and mass drug administration .
In general , the proportion of a population receiving an intervention was associated with improved health .
We found evidence of publication bias for certain spillover estimates but not for total or direct effects .
Conclusions We found the strongest evidence for spillovers from vaccines and mass drug administration to control infectious disease .
There was little high quality evidence of spillovers for other interventions
Background Many interventions delivered to improve health may benefit not only direct recipients but also people in close physical or social proximity .
Our objective was to review all published literature about the spillover effects of interventions on health outcomes in low-middle income countries and to identify methods used in estimating these effects .