Background: BCG and oral polio vaccines (OPV) at birth are associated with beneficial non-specific effects, reducing neonatal mortality by more than what can be explained by prevention of the target diseases. BCG is recommended at birth, but is often given much later, especially in rural areas. In two RCTs in Guinea-Bissau, BCG-at-birth reduced neonatal mortality in low birthweight (<2500g; LBW) children by 48% (95%CI: 18-67%) and in children with a birthweight >2500g (NBW), OPV+BCG vs BCG was associated with a 32% (95%CI: 0-55%) lower mortality.