Flu vaccinations are being urged as cases rise. So, how effective is this winter's jab?

Influenza activity in Australia typically peaks between June and September, but infections can occur year-round. (Pexels)

Australia had a couple of virtually flu-free years, but the disease has bounced back — and then some — over the past few weeks.

In the year to last Sunday, almost 40,000 influenza cases were reported to the National Notifiable Diseases Surveillance System, with 26,000 of those cases in the fortnight of May 9-22.