[Postmarketing surveillance of secondary effects of vaccines]

Despite a continuous search for safer and more efficacious vaccines, adverse events continue to occur following vaccine administration. Adverse events are usually mild. Serious adverse events that could result in death or permanent sequelae are extremely rare. In all cases, benefits associated with immunization greatly outweigh the risks. Due to the large number of doses administered, it is probable that there are purely temporal associations between some adverse events and vaccine administration. Since immunization is sometimes mandatory with vaccines usually administered to healthy individuals and their benefits expanded to the community at large, adverse events are difficult to accept. Primary objectives of vaccine-associated adverse events surveillance is the early detection and appropriate and quick response to such events in order to lessen the negative impact on immunization programs and on the health of the individuals. Specific aspects of vaccine postmarketing surveillance are presented.