A global perspective on vaccine safety.

"Immunization Safety" (i.e., ensuring and monitoring the safety of all aspects of immunization, including vaccine quality, storage and handling, vaccine administration and the disposal of sharps) remains a major challenge. Any vaccine safety issue, real or perceived, may lead to rumors and undermine confidence in vaccination and, ultimately, have dramatic consequences for immunization coverage and disease incidence. In 1999, WHO's Department of Vaccines and Biologicals launched the Immunization Safety Priority Project to establish a comprehensive system to ensure the safety of all immunizations given in national immunization programmes. The project aims at strengthening each country's capacity. The principal areas of activity of the project include: research and development of safer vaccines and safer and simpler vaccine delivery technologies; assurance of vaccine safety through quality control procedures and quality specifications; implementation of tools to ensure vaccine quality up to vaccine administration; access to safe and efficient vaccine administration technologies and their disposal; and identification and management of risks related to immunization. This report focuses on the latter area and highlights challenges and critical factors in establishing a safety profile for a vaccine and the importance and limits of post market surveillance. It presents some of WHO's supporting activities among which the establishment of a Global Advisory Committee on Vaccine Safety to provide an independent scientific assessment of vaccine safety issues. WHO has a role to play not only because of its technical and normative role but also because of its privileged relation with country authorities and its global vision and mandate and being perceived as neutral and free of conflicts of interest.