A type of influenza that caused several deaths six years ago has taken over from swine flu as the dominant strain this winter.
The 'B Brisbane' strain is the main one circulating, but both it and the swine flu are covered by this year's vaccination.
Virologists say the B Brisbane strain, which also targets children, is linked to another from the B lineage which caused an outbreak during which three babies died in 2005.
In 2009, a pandemic was declared because of high levels of the influenza A H1N1 (swine flu) virus.
Officials say 993,000 people have been vaccinated for flu so far this year and they are expecting normal levels of flu this year.