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 .
Users identified challenges in applying GRADE to complex interventions and suggested an extension to GRADE.
OBJECTIVES To explore user perspectives on applying the Grading of Recommendations Assessment , Development and Evaluation ( GRADE ) to systematic review s of complex interventions . STUDY DESIGN AND SETTING Thirty-three authors of recent ( 2013 onward ) systematic review s were contacted regarding their perspectives on using  GRADE from three Cochrane review groups : Cochrane Developmental , Psychosocial , and Learning Problems Group ; Cochrane Public Health Group ; and Cochrane Depression , Anxiety , and Neurosis Group . Framework Analysis was applied to the data to identify the challenges in applying GRADE and suggestions for its extension , that is , adaptation . These two themes were cross-compared between the groups of answers from " simple " vs. " complex " intervention review authors to identify the specific perspectives on using GRADE in review s of complex interventions . RESULTS Specific challenges were identified in applying GRADE to review s of complex interventions . These were related to the assessment of nonr and omized studies and performance bias in GRADE . Authors perceived these challenges to contribute to frequent downgrading of the " best evidence possible " for complex interventions . Meanwhile , GRADE was found to lack an analytic approach to enable adequate evidence synthesis and assessment of intervention implementation elements . CONCLUSION Users suggest that the GRADE guidance be extended to address-specific considerations for complex interventions
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 .