A pre-winter flu virus is sweeping the country, prompting health officials to urge New Zealanders to get an early flu shot.
It is the same A (H1N1) flu strain, commonly known as swine flu, that caused the 2009 pandemic and struck down 780,000 people, and one in every three school children.
Already this year, eight cases have been reported at Hawke's Bay Hospital.
One woman, aged in her 50s, has been in a critical condition in intensive care there for 13 days.
A Wellington workplace was affected last month and people have been found with the acute illness in Christchurch and Oamaru this week.
Two cases of H1N1 have been also been confirmed in the small South Canterbury farming town of Geraldine.
The early season flu has hit the town badly, nearly closing the local GP after its staff were laid low with the virus, and also running through the local supermarket.
Director of Public Health, Dr Darren Hunt said national surveillance of influenza-like illness indicates that the spread of the virus is "at about the same level that we would expect to see at this time of year".
However, virologist Dr Lance Jennings said it was rare for a flu to spread so widely through a community.
"There is something unusual going on," he said yesterday (WED).
Given that people have been hospitalised with the sickness, Dr Jennings - a spokesman for National Influenza Specialist Group - said it highlighted the fact that flu could be a serious disease and that it could hit some people harder than others.
While the flu season normally peaked mid-winter, the recent cases meant people should get immunised now and not wait until they felt the sniffles.
"[It] gives you the best chance of being protected," Dr Jennings said.
"Although this particular virus can lead to serious complications for pregnant women and younger, previously healthy people, the good news is it is covered by the 2014 vaccine.
"So we strongly advise people to talk to their doctor or nurse soon to arrange a vaccination."
Influenza activity has been high during the North American winter, with H1N1 the prominent virus, and at its highest levels since 2009.
The flu affecting North America is usually a good indicator of what to expect in a New Zealand winter.
The anti-viral medicine sold here under the name Tamiflu is seen as the most effective way to combat H1N1.
It's not clear how many cases of flu there have been in New Zealand this year, as it's not a notifiable disease.
More than 540,000 people had already been given a flu shot, the Ministry of Health confirmed yesterday.
It has set a target of 1.2 million people vaccinated by the end of July.
Even fit, tough rugby players aren't immune from the virus.
The entire Crusaders squad got their flu shot after a training session this week.
"During the rugby season there's no time to be sick," said coach Todd Blackadder.
Pregnant women and their newborn babies are at particular risk of catching the virus, and Dr Jennings urged them to get immunisation.
It is free from a GP or nurse until July 31, 2014 for New Zealanders at high risk of complications - pregnant women, people aged 65 and over, and anyone under 65 years of age, including children six months and older, with long-term health conditions such as heart disease, stroke, diabetes, respiratory disease (including asthma), kidney disease and most cancers.
* Wash and dry hands often
* Stay away from people who are sick
* Stay away from work or school if unwell
* Cover coughs and sneezes