Association Between Residence in Flood-Prone Areas and Incomplete Childhood Vaccination Coverage in Bangladesh

IntroductionFlooding events, which are strongly linked to climate change and variability, have the potential to disrupt communities and health systems. Vaccination, a highly effective public health intervention, plays a pivotal role in preventing numerous deaths annually, particularly among children. However, the relationship between exposure to flood events and early childhood vaccination remains unexplored. MethodsThis study utilizes validated flood exposure data from the Global Flood Database (GFD) and five waves of nationally representative survey data regarding the vaccination history of children under 3 years from the Bangladesh Demographic and Health Surveys (DHS) collected between 2004 and 2018. Using the geographical coordinates of each surveyed household grouping and matching it with the spatially resolved GFD data, we determined whether children reside in a flood-prone area. We then used Generalized Estimating Equations, accounting for geographical clustering and including an inverse probability of treatment weighting (IPTW) for covariate balance, to assess the relationship between living in a flood-prone area and incomplete vaccination. Incomplete vaccination was defined as having missed at least one does of the four World Health Organization-recommended childhood vaccines: Tuberculosis (BCG), Diphtheria-Tetanus-Pertussis (DTP), Polio (OPV), and Measles (MCV). The sensitivity of the association measure to various definitions of exposure was explored. ResultsOur sample included 13,649 children, of which 16% resided in flood-prone areas and 84% were fully vaccinated. Our findings indicate that children living in a flood-prone area have a higher risk of not receiving the DTP vaccine (PR = 1.24, CI: 1.05-1.46), the BCG vaccine (PR = 1.27, 1.08-1.50), and the OPV vaccine (PR = 1.24, CI: 1.06-1.46). The direction of the relationship remained but the effect became non-significant when looking at the MCV vaccine alone (PR = 1.06, CI: 0.90-1.25), as well as the four vaccines together (PR = 1.05, CI: 0.90, 1.22). InterpretationThese findings hold critical implications for disaster management protocols, emphasizing the need to ensure uninterrupted access to routine healthcare services during floods, which are becoming increasingly more common due to climate change. Considering that populations in low- and middle-income countries are disproportionately impacted by extreme climate events such as floods and that preventable infectious diseases remain among the leading causes of child death in these regions, ensuring access to essential vaccines is critical for safeguarding public health.