Annual report of the National Influenza Surveillance Scheme, 2002

Surveillance for influenza in Australia in 2002 was based on notifications to the National Notifiable Diseases Surveillance system from all states and territories, national and state-based sentinel practice consultations for influenza-like illness and reports of influenza virus isolations from a laboratory network. The impact of influenza was assessed by absenteeism data from a major national employer. Influenza A was the dominant type, 99 per cent of which were subtype H3N2 with only a single H1 isolate, which was identified as H1N2. The H3N2 isolates were closely related to the vaccine strain A/Moscow/10/99 and the A/Panama/2007/99, with less than one per cent showing genetic variation. Influenza B made up 21 per cent of circulating influenza and the majority of B strains were of the B/Victoria lineage, but had a haemagglutinin closely related to the B/Hong Kong/330/2001 strain. This strain was associated with two outbreaks but a proportion of vaccinees with the 2002 vaccine showed protective antibody titres. The 2002 influenza vaccine was given to 77 per cent of Australians over 65 years.