Effect of a campaign with oral polio vaccine on general health: A cluster-randomised trial in rural Guinea-Bissau

Objectives: To investigate in a cluster-randomised trial whether a campaign with oral polio vaccine (C-OPV) reduced mortality and morbidity. Methods: We randomised 222 village clusters under demographic surveillance to an intervention (health check and C-OPV) or control group (health check only). Children aged 0–8 months were eligible. In Cox proportional hazards models with age as the underlying timescale, we compared rates of non-accidental mortality/hospital admission (composite primary outcome) during 12 months of follow-up. Secondary analyses considered non-accidental admission and mortality as separate outcomes. Potential effect modifiers identified in prior studies including sex, season, and timing of the first routine OPV dose (OPV0, scheduled at birth) were assessed. Results: Among 10,175 children (5288 in 111 intervention clusters/4887 in 111 control clusters), we observed 265 deaths/admissions during 7616 person-years at risk (intervention: 129; control: 136). C-OPV did not reduce the composite endpoint, hazard ratio (HR): 0.87, 95%CI: 0.68–1.12 or its separate components. C-OPV reduced the risk in children receiving OPV0<15 days of birth (HR=0.66, 95%CI: 0.46–0.95), but not in other children (p for interaction: 0.03). Interactions for other potential effect modifiers were not statistically significant. Conclusions: C-OPV had no overall effect on mortality/admissions, but the effect differed by early priming with OPV0.