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The following errors were discovered in this article: The third row of Figure 1 was mislabelled; the result for the row for Ali et al., 2013 in Table 1 was mislabelled; in Table 3, the rows for Contreras and Maitra, for Avitabile 2012 and for German et al had errors; two studies were omitted from Figure 3B; the values for % cholera vaccine coverage for Emch et al., 2009 in Supplement 7, Figure 2 were incorrect; and "quality of evidence" values for Ali et al., 2013 and for Cooper and Fitch 1983 were incorrect.

BackgroundMany 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.MethodsWe searched 19 electronic databases for articles published before 2014 and hand-searched titles from 2010 to 2013 in five relevant journals. We adapted the Cochrane Collaboration's quality grading tool for spillover estimation and rated the quality of evidence.ResultsA total of 54 studies met inclusion criteria. We found a wide range of terminology used to describe spillovers, a lack of standardization among spillover methods and poor reporting of spillovers in many studies. We identified three primary mechanisms of spillovers: reduced disease transmission, social proximity and substitution of resources 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. Most studies were of moderate or low quality. We found evidence of publication bias for certain spillover estimates but not for total or direct effects. To facilitate improved reporting and standardization in future studies, we developed a reporting checklist adapted from the CONSORT framework specific to reporting spillover effects.ConclusionsWe 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.