Allergic reactions to vaccines.

Abstract Vaccines have had a very significant impact in Human Health. Except for public water supply and sanitation measure, no other single public health intervention induced such a significant reduction in disease incidence and child mortality. In Portugal, a National Vaccination Program (NVP) began in 1965 and more recently, in January 2006, the new NVP was implemented. However, it is important to recognize and understand adverse reaction to vaccines, since this therapy is intended to be administered to healthy individuals, a fact which considerably lowers the threshold of acceptability of adverse reactions by the general public. In such a way, better understanding of vaccine adverse reactions allows a correct diagnosis and a more appropriate selection of vaccines, increasing the acceptance of immunization in the community.