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 .
Relationship between neighbourhood-level killed oral cholera vaccine coverage and protective efficacy: evidence for herd immunity.
OBJECTIVES The effectiveness of vaccines in population s must consider both direct and indirect protection . This study reanalyses data from a large individually r and omized oral cholera vaccine trial that was conducted in rural Bangladesh from 1985 to 1990 . A recent analysis of the results of that trial showed that the proportion of people in household clusters who received the vaccine was inversely related to placebo incidence during the first year of surveillance , which was attributed to herd immunity . METHODS In this study we measure the relationship between  neighbourhood-level oral cholera vaccine coverage and protective efficacy ( PE ) during a 2 year follow-up period , controlling for known effect modifiers . We link trial data to a household geographic information system to facilitate the neighbourhood-level analysis . Findings Neighbourhood-level PE can be partially explained by vaccine coverage after adjusting for ecological variables . CONCLUSIONS The inverse relationship between vaccine coverage and efficacy illustrates that people living in high-coverage areas may be indirectly protected from cholera because people living around them are vaccinated
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 .