Surveillance of adverse events following immunisation: Australia 2002 to 2003.

Reports of suspected adverse events following immunisation (AEFI) are reviewed by the Adverse Drug Reactions Advisory Committee and collated in a central database. We analysed AEFI records for vaccines administered during October 2002 to December 2003, and assessed AEFI reporting trends for 2000 to 2003. AEFI reporting rates were calculated using denominator data from the Australian Childhood Immunisation Register and the annual national influenza vaccination coverage survey. A total of 1,744 AEFI records were analysed for October 2002 to December 2003. The majority described non-serious events; 9 per cent (n=149) described AEFIs defined as 'serious'. Four deaths were reported but none were causally related to immunisation. Dose-based AEFI reporting rates were 2.1 per 100,000 doses of influenza vaccine for adults aged 40 years or over and 19.8 per 100,000 doses of scheduled vaccines for children aged <7 years. The most frequently reported individual AEFI was injection site reaction in children after a fourth or fifth dose of an acellular pertussis-containing vaccine (54 and 98 reports per 100,000 doses respectively). The most frequently suspected vaccine was meningococcal C conjugate vaccine (34% of reports-mostly injection site reactions, gastrointestinal symptoms and headaches). The average annual reporting rate was 7.0 per 100,000 population, the highest to date. The increase in the AEFI reporting rate was due to a greater number of children becoming eligible to receive a fourth or fifth consecutive dose of acellular pertussis vaccine and the introduction of the meningococcal C vaccination program in January 2003 for those aged 1-19 years. The low reporting rate of serious AEFIs demonstrates the high level of safety of vaccines in Australia.