Doctors in the Northern Hemisphere often pay close attention to how the flu season across the equator -- which takes place during our summertime -- has gone as an indicator of what kind of flu season we could be in for this winter. That's why they're worried.
This year's flu shot was not especially effective in Australia, where the H3-N2 strain proliferated. It's a subtype of the Influenza-A strain, which tends to cause more challenging-than-normal symptoms, in particular amongst the very old and the very young. It's also not a subtype that your annual flu shot is generally very good at protecting you against (it's designed to stop Influenza-B and H1N1).
Already, physicians say there is a mixed bag of viral strains circulating across the country, which presents challenges to the targeted annual vaccine's effectiveness.
Of course, doctors also say that even a less-effective vaccine is better than no vaccine at all as flu season fast approaches.