Reporting of adverse events following immunization in Australia.

It is an important component of any immunization programme that vaccine safety is monitored by carrying out surveillance for adverse events following immunization (AEFI). Such surveillance can be active or passive. Active surveillance will detect more AEFI, but the vast majority will be minor events. Passive surveillance is probably more appropriate for routine AEFI surveillance, while active surveillance can be used to monitor a new vaccine or to test whether a specific severe event is significantly associated with immunization. Australia has a predominantly passive surveillance system. The system has recently been centralized, providing useful national data on vaccine safety.