This second edition, which includes revised guidelines for managers of immunization programs, will assist managers in national regulatory authorities and immunization programs to establish/strengthen immunization safety surveillance system.It provides guidelines for those responsible for vaccine safety and quality on the following: * strategies and systems for ensuring quality and safety of vaccines * new classification of AEFIs and the objectives of immunization safety/AEFIs surveillance * understanding vaccine reactions for better decision-making * AEFI surveillance systems: reporting, investigating, causality assessment and responding processes * best use of surveillance data, and * communication strategy on immunization safety for the public and the media.