Effectiveness of seasonal influenza vaccine in Australia, 2015: An epidemiological, antigenic and phylogenetic assessment
Section snippets
Background
Since 2010, the number of notified laboratory confirmed influenza cases in Australia increased by an average of 63% annually to a record 100,582 in 2015 [1]. Notified cases in 2015 were predominantly type B, which was unusual for two reasons. First, there is a widely held belief that seasons dominated by influenza B viruses are mild. However, while this was somewhat reflected in outpatient surveillance data, the large number of notified cases suggested otherwise [2]. Second, influenza seasons
Methods
The Australian Sentinel Practices Research Network (ASPREN), the Victorian Sentinel Practice Influenza Network (VicSPIN), and the Sentinel Practitioners Network of Western Australia (SPNWA) constitute Australia’s three sentinel general practice (GP) networks for influenza surveillance. SPNWA and VicSPIN operate in the respective states of Western Australia and Victoria, whilst ASPREN GPs are primarily located in the other six states and territories, except for several in Victoria.
The sentinel
Participant recruitment
The 354 GPs participating in the three systems conducted 627,381 consultations during the study period, of which 5968 (1%) were reported as meeting the ILI case definition; swabs were collected from 2983 of these ILI patients (50%). Cases of influenza were detected in every week of the study period, with a peak in the number of detections (n = 102) and percent positive (50%) in the weeks ending 9 August (week 31) and 23 August (week 33), respectively (Fig. 1). After exclusion of 540 records
Discussion
The 2015 influenza season in Australia was characterised by the predominance of type B viruses, the first year this has been observed since 2008 [24]. With an overall point estimate of 58%, the vaccine provided moderate protection against type B influenza. Consistent with the composition of the TIV (which we assumed most vaccine recipients received), the VE point estimate was higher against B/Yamagata influenza (71%) than viruses from the B/Victoria lineage (42%). This observation is further
Conflict of interest statement
All authors report that they do not have a commercial or other association that might pose a conflict of interest.
Acknowledgements
We thank the general practitioners that participated and contributed to ASPREN, VicSPIN and SPNWA in 2015. We also thank laboratory staff members from the following laboratories who undertook influenza testing: and virus characterisation: SA Pathology, Adelaide, South Australia; PathWest Laboratory Medicine WA, Perth, Western Australia; the Victorian Infectious Diseases Reference Laboratory, Melbourne, Victoria; and the WHO Collaborating Centre for Reference and Research on Influenza,
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2018, VaccineCitation Excerpt :Because of the near absence of influenza A(H3N2) circulation in other regions of the northern hemisphere, there are very few estimates to compare with. However, from the US a VE of 43% was reported in the 2015–2016 season [13] and Australia reported a VE of 44% for the 2015 southern hemisphere season [26]. Later in the 2015–2016 season, in Beijing as well as in other regions of the northern hemisphere, influenza B/Victoria lineage dominated, which was not contained in the 2015–2016 TIV.
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2018, VaccineCitation Excerpt :Influenza A or B vaccine effectiveness was 64–68% by either full or partial vaccination and 66–73% by full vaccination. These results were comparable to those of a Hong Kong study between 2009 and 2013 (62% vaccine effectiveness for influenza A or B hospitalisation) [3] and studies of other high income countries (60% in the United States [10] and 68% in Australia [11]). Hong Kong had a severe winter influenza season in 2014/2015 due to a strain mismatch with the recommended Northern Hemisphere vaccine.