Statistical Analyses by State.

BackgroundCholera outbreaks are surging worldwide. Growing research supports case-area targeted interventions (CATIs), whereby teams provide a package of interventions to case and neighboring households, as an effective strategy in cholera outbreak control, particularly in humanitarian settings. While research exists on individual CATI interventions, research gaps exist on outcomes of integrated interventions during CATI responses.Methodology/Principal findingsWe conducted a prospective observational cohort study on CATIs during the 2021 cholera outbreak in Northeast Nigeria. During CATI response in Borno, Adamawa, and Yobe, research enumerators accompanied CATI teams to households and observed interventions (including provision of soap, Aquatabs, educational materials, and jerrycans; latrine and bedding disinfection; and hygiene promotion) and collected data on demographics, existing household water, sanitation, and hygiene, and household water free chlorine residual (FCR). Enumerators returned to households 10–14 days later to conduct follow-up surveys. We tested differences in reported delivery and receipt of interventions, and household drinking water FCR concentrations before and after CATIs. We also analyzed the associated relationship between CATI and environmental factors and odds of FCR Conclusions/SignificanceThese findings suggest that CATIs improved household drinking water FCR, a key protective measure against cholera, in Northeast Nigeria. Our research highlights factors associated with FCR concentrations