A marked spike in flu rates has prompted health officials to urge people to get a flu jab before a free immunisation campaign finishes on July 31.
In the past month the number of patients suffering from influenza-like illness has more than doubled in Auckland, from 40.9 per 100,000 to 96.8.
Flu rates are also above normal for this time of year in Waitemata, South Canterbury, Wellington, Waikato, Taranaki and Hawke's Bay, the Health Ministry's National Influenza Specialist Group says.
The Inland Revenue Department in part is blaming winter illness for almost a third of calls from taxpayers going unanswered.
Almost one million New Zealanders have had the vaccination, which this year covers three influenza A and B strains, including the severe A(H3N2) virus.
"Even though we're seeing a rise in influenza-like illness... it's not too late to be vaccinated and it's still your best form of protection against influenza," virus expert and specialist group spokesman Dr Lance Jennings said.
Anyone who wants to be immunised against influenza after July 31 will have to pay a small charge.
Immunisation is free for those at high risk of more severe disease and complications, including pregnant women, people aged 65 and over, and anyone with on-going health conditions such as heart disease, strokes, diabetes, respiratory disease (including asthma), kidney disease and most cancers.
Canterbury residents also qualify for free vaccination if they are aged between six months and 18 years old.
It's estimated more than 400 people die each year directly or indirectly because of influenza.