Flood-prone areas linked to missed childhood vaccines in Bangladesh

Flooding events, increasingly tied to climate change and variability, can disrupt communities and health systems — with possible consequences for routine care like childhood vaccination. To explore this concern, researchers led by Emilie Schwarz combined validated flood exposure information with long-running national survey data to see if children living in flood-prone places were less likely to be fully vaccinated. The team used the Global Flood Database (GFD) to identify areas prone to flooding and matched those spatial records to household locations recorded in five waves of the Bangladesh Demographic and Health Surveys (DHS) covering 2004 to 2018. They focused on vaccination histories for children under 3 years and determined flood exposure by linking each surveyed household’s geographical coordinates with the GFD. By bringing together geographic flood data and representative health survey data, the study set out to measure whether living in an area prone to floods was associated with incomplete routine childhood vaccination — a question that had not been previously examined at this scale in Bangladesh.

The analysis included 13,649 children, of whom 16% resided in flood-prone areas and 84% were fully vaccinated under the study definition. Incomplete vaccination was defined as having missed at least one dose of the four World Health Organization-recommended childhood vaccines: Tuberculosis (BCG), Diphtheria-Tetanus-Pertussis (DTP), Polio (OPV), and Measles (MCV). To estimate associations the researchers used Generalized Estimating Equations to account for geographic clustering and applied an inverse probability of treatment weighting (IPTW) approach to balance covariates between groups. They also tested how sensitive the results were to different ways of defining flood exposure. The key findings showed higher risks for not receiving specific vaccines among children in flood-prone areas: DTP (PR = 1.24, CI: 1.05-1.46), BCG (PR = 1.27, 1.08-1.50), and OPV (PR = 1.24, CI: 1.06-1.46). The association remained in the same direction but became statistically non-significant for MCV alone (PR = 1.06, CI: 0.90-1.25) and for the combined measure of all four vaccines (PR = 1.05, CI: 0.90, 1.22).

These findings have immediate relevance for planning and response in flood-prone settings. If children who live where flooding is more likely are at higher risk of missing routine vaccines like BCG, DTP and OPV, then disaster management and public health systems need to protect access to those services when floods occur. The study highlights that flood exposure can be a barrier to preventive care, and that routine vaccination programs should be considered essential services that require continuity during weather-related disruptions. Given that extreme climate events disproportionately affect low- and middle-income countries and that preventable infectious diseases still contribute heavily to child death in these regions, ensuring uninterrupted access to the vaccines named in this study is a concrete step toward safeguarding child health. The results suggest policymakers and health planners should prioritize maintaining vaccination access in flood-prone communities as part of climate adaptation and disaster preparedness.