Abstract
Immunization, one of the most successful and cost-effective public health interventions for reducing infant and child morbidity and mortality globally has been passing, in recent times, by a crisis of acceptance by the lay public, which has greatly reduced vaccine coverage worldwide. This article presents the importance of vaccines for individual and collective health, discusses about some adverse effects and the reasons for refusal to vaccinate, and proposals to overcome these barriers and to increase the effectiveness of vaccination programs.