Article TextOriginal researchImpact and effect mechanisms of mass campaigns in resource-constrained health systems: quasi-experimental evidence from polio eradication in NigeriaBackground Mass campaigns are a key strategy for delivering life-saving interventions under Global Health Initiatives, especially in weak health system contexts. They are frequently designed parallel to the health system to rapidly achieve programme targets such as vaccination coverage, but we lack quantitative evidence demonstrating their impact and effect mechanisms on health system performance at sub-/national...…Article TextOriginal researchImpact and effect mechanisms of mass campaigns in resource-constrained health systems: quasi-experimental evidence from polio eradication in NigeriaBackground Mass campaigns are a key strategy for delivering life-saving interventions under Global Health Initiatives, especially in weak health system contexts. They are frequently designed parallel to the health system to rapidly achieve programme targets such as vaccination coverage, but we lack quantitative evidence demonstrating their impact and effect mechanisms on health system performance at sub-/national...WW…