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 2012-2019 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 campaigns with OPV-only (C-OPV) versus before C-OPV to assess the “intention-to-treat”-effect of C-OPV. We allowed for different baseline hazard function in the two periods (2004-2011, 2012-2019), with separate models for each period. In the main analysis children were only followed prospectively. Findings: In the main analysis, including 736 deaths (2.0%) among 36,155 children, the HR for after C-OPV was 0.68 (95% confidence interval: 0.51-0.90). No other type of health campaign had similar beneficial results. Each additional dose of C-OPV lowered the mortality rate by 8% (0 to 15%). The number needed to treat (NNT) with C-OPV to save one life between 0-35 months of age was only 109 (100-119) (data not shown). Interpretation: This is the fourth study to show that C-OPV has huge beneficial non-specific effects on child survival. No study has found the opposite. Stopping OPV as planned could have detrimental effects for overall child health in low-income countries. Funding Statement: This research study is funded by core donors who provide unrestricted support to icddr,b for its operations and research. icddr,b is grateful to the Government of Bangladesh, Canada, Sweden and the UK for providing core/unrestricted support. The work on non-specific effects of vaccines has been supported by the Danish Council for Development Research, Ministry of Foreign Affairs, Denmark [grant number 104.Dan.8.f.], Novo Nordisk Foundation and European Union FP7 support for OPTIMUNISE (grant: Health-F3-2011-261375). Declaration of Interests: Nothing to declare. Ethics Approval Statement: Ethical Review Committee of International Centre of Diarrhoeal Disease Research, Bangladesh provided approval for the study.