Abstract
INTRODUCTION: Despite global commitments to eliminate malnutrition, over half the world's population remains affected. Multisectoral nutrition interventions targeting both proximate and distal causes of malnutrition are essential across the lifespan. Yet, current data collection lacks comprehensive nutrition intervention coverage measures, risking inaccuracies in tracking progress. The One Nutrition Coverage Survey (ONCS) aims to test new and refined coverage measurement methods, assess coverage equity and guide integration into large-scale household surveys. METHODS AND ANALYSIS: The ONCS will be a cross-sectional, population-representative household survey conducted in four districts of Bangladesh (Rangpur, Sylhet, Dhaka and Khulna), selected for their geographic spread and urban-rural balance. A stratified multistage sampling approach will be used to select enumeration areas, and a total of approximately 3280 households randomly selected within each EA will be included in the survey. The survey will interview women of reproductive age (15-49 years), caregivers of children (0-9 years), adolescents (10-19 years) and pregnant women, collecting data on multisectoral nutrition interventions relevant to these groups. It will use both existing and new measures, while also capturing monetary and non-monetary costs for survey design to implementation. Data will be analysed to assess coverage, co-coverage and equity by sociodemographic characteristics, as well as the feasibility, accuracy and costs of the survey approach. ETHICS AND DISSEMINATION: The study protocol and instruments were reviewed and approved by the International Centre for Diarrhoeal Disease Research, Bangladesh's (icddr,b) Ethical Review Board in Bangladesh and the International Food Policy Research Institute's Institutional Review Board in Washington, DC, USA. Adults provided signed informed consent and adolescents their assent. Findings will be shared through peer-reviewed publications, conferences and presentations in Bangladesh with key stakeholders. This study will yield new tools, methods and evidence for measuring multisectoral nutrition intervention coverage, applicable to other low-income and middle-income countries. Learnings from ONCS will enhance data collection aligned with national strategies, helping governments improve coverage assessments, inform decisions and strengthen programme monitoring.