Annual report of the National Influenza Surveillance Scheme, 2001.

Surveillance of influenza in Australia in 2001 was based on data from national and state-based sentinel practice consultations for influenza-like illness, laboratory isolations of influenza virus and absenteeism rates from a national employer. In 2001, laboratory-confirmed influenza became a notifiable disease and was reported to the National Notifiable Diseases Surveillance System (NNDSS). Influenza A was the dominant type, 81 per cent of which were subtype H1N1 and 19 per cent were subtype H3N2. The influenza A (H1N1) analysed were all A/New Caledonia/20/99-like strains. The H3N2 isolates were antigenically similar to the reference strain A/Moscow/10/99 and the vaccine strain A/Panama/2007/99. The influenza B isolates, which made up only 10 per cent of all isolates, were mainly B/Sichuan/379/99-like strains but 10 per cent of isolates were more closely related to B/Harbin/7/94-like viruses, which circulated in previous years. The Australian 2001 influenza vaccine represented a good match for the circulating viruses and 77 per cent of persons over 65 years in Australia were vaccinated in 2001.