Current Report Summary
- The seasonal increase in influenza activity has slowed. Influenza activity remains relatively low compared to 2011 and 2012.
- Since the beginning of the year there have been 14,068 laboratory confirmed cases of influenza reported. Over the past fortnight there were 3,262 notifications, with almost half reported from New South Wales (1,419).
- Nationally, whilst influenza A remains the predominant influenza virus type, the proportion of influenza B this season has been higher than recent years. During the 2012 season there were very few notifications of influenza A(H1N1) pdm09. So far in 2013, whilst the majority of influenza A reports are unsubtyped, approximately 15% of overall notifications have been reported as influenza A(H1N1)pdm09.
- Across jurisdictions the distribution of influenza types and subtypes is variable. In Western Australia, influenza A(H3N2) remains the predominant subtype, however the proportion of A(H1N1)pdm09 is increasing. Influenza type B continues to represent over half of Victoria's influenza notifications. In recent weeks there have been increasing proportions of influenza B in South Australia, Queensland and New South Wales.
- Notification data show that there is a predominance of influenza B infections in those aged less than 15 years, with influenza A infections peaking in the 0-4 and 30-34 years age groups. Consistent with A(H1N1)pdm09 dominant years, there are very few notifications of this subtype in those aged 65 years and over.
- Over the past few weeks the rate of seasonal increase in influenza associated hospitalisations has stabilised. Almost 15% of influenza cases have been admitted directly to ICU. The age distribution of hospital admissions shows peaks in the 0-9 and over 60 years age groups.
- The WHO has reported that influenza activity in the northern hemisphere temperate zones remains at inter-seasonal levels. In the temperate countries of South America and Southern Africa, influenza transmission peaked in late June and was primarily associated with influenza A(H1N1)pdm09.
- Australian Influenza Surveillance Report No.06, 2013 (PDF 1495 KB)
- Australian Influenza Surveillance Report No.06, 2013 (Word 1692 KB)
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