This paper provides a theoretical and empirical investigation of the positive complementarities between disease-specific policies introduced by competing risks of mortality. The incentive to invest in prevention against one cause of death depends positively on the level of survival from other causes. This means that a specific public health intervention has benefits other than the direct medical reduction in mortality: it affects the incentives to fight other diseases so the overall reduction in mortality will, in general, be larger than that predicted by the direct medical effects. We discuss evidence of these cross-disease effects by using data on neo-natal tetanus vaccination through the Expanded Programme on Immunization of the World Health Organization.