Immunologists are busy working on the vaccine for next year's flu pandemic.
The director of Auckland University's Immunisation Advisory Centre, Nikki Turner, is undertaking a five-year project on influenza in New Zealand.
She said the flu vaccine was between 50 and 60 percent effective, but that could vary depending on the strain in circulation.
"There is still a certain flu type A that is problematic and is not always matched well-matched to the vaccine. So my understanding is that they are going to change the vaccine again slightly to try and get a better match for next year."