National immunisation campaigns with oral polio vaccine may reduce all-cause mortality: Analysis of 2004–2019 demographic surveillance data in rural Bangladesh

Background: West African studies have suggested that national immunisation campaigns with oral polio vaccine (C-OPV) may non-specifically reduce all-cause child mortality rate by 15–25%. We investigated whether C-OPVs had similar non-specific effects in rural Bangladesh from 2004 to 2019. Methods: Chakaria, is a health and demographic surveillance system (HDSS) in Southern Bangladesh. From 2004–2011 the HDSS covered a random sample of households; from 2012 to 2019 it covered a random sample of villages. Using Cox proportional hazards models, we calculated hazard ratios (HR) comparing mortality for children under 3 years of age after C-OPV versus before C-OPV to assess the effect of receiving a C-OPV. We allowed for different baseline hazard function in the two periods (2004–2011, 2012–2019), with separate models for each period. Findings: There were 768 deaths (2.1%) amongst 36,176 children. The HR after C-OPV was 0.69 (95% confidence interval: 0.52–0.90). National campaigns providing vitamin A or measles vaccine did not have similar effects. Each additional dose of C-OPV was associated with a reduction in the mortality rate by 6% (−2 to 13%). The number needed to treat with C-OPV to save one life between 0 and 35 months of age was 88 (81–96). Interpretation: This is the fourth study to show that C-OPV has beneficial non-specific effects on child survival. All studies have shown a beneficial effect of C-OPV on child health. Stopping OPV as planned after polio eradication without any mitigation plan could have detrimental effects for overall child health in low-income countries. Funding: The Chakaria HDSS was funded by international sponsors. No sponsor had any influence on the preparation of the article.