Health Minister Jonathan Coleman today announced the influenza immunisation programme will be extended until the end of next month.
The extension follows reports that an unusual pattern of sickness is developing in the North and South Islands, with health professionals recording peaks of different influenza strains - something not seen in more than 30 years.
"Ministry of Health surveillance suggests that influenza has not yet peaked this winter. To help ensure people have the protection they need we are extending the funded vaccination season until 31 August," Dr Coleman said.
"The A-H3N2 strain, which is covered by the vaccine, appears to be the predominant type - this strain affects the elderly and very young more severely than other strains."
The influenza vaccine is also free for people with Down Syndrome and those with cochlear implants.
"Although the vaccine was delayed worldwide by a few weeks, the health sector has quickly caught up with previous years' distribution," says Dr Coleman.
As of today, almost 1.19 million flu vaccines have been distributed across the country, protecting over a quarter of our population.
"I think we're about 17,000 doses shy of last year's record of 1.20 million doses distributed, so it would be nice to reach that target and protect those at greatest risk and who haven't received their vaccine as yet."
As the Southern Hemisphere influenza season was still getting under way, there was no data on whether any new viruses had been discovered yet.
However, samples were sent to the World Health Organisation's southern hemisphere laboratory in Melbourne last week.
Dr Lance Jennings, Canterbury District Health Board virologist and spokesman for the National Influenza Specialist Group, put a dampener "one of the myths" about the effectiveness of the flu jab.
"There is always that 'oh I got the flu jab and I developed the flu afterwards' but there are other respiratory viruses that result in considerable burdens in terms of hospitalisation of young children with pneumonia-like conditions and that's prevalent at the moment as well. There are also other viruses that mimic influenza."
Dr Jennings said not much could be done about preventing the respiratory viruses currently circulating.
Data obtained by the Herald from the Environmental Science and Research latest influenza report, dated July 5, reveals there has been 131 reports of the A strain in the North Island this season, compared with two in the South Island.
Reports of influenza-like illnesses were peaking so fast they had almost reached the total number for last year, despite two months of the flu season to go.
Concern about the virus spreading is high as children head back to school next week.
Dr Jennings warned North Islanders battling Influenza A that they would get hit by Influenza B.
"I suspect what we're going to see in the North Island is the H3N2 [A] virus dominating and then as the season progresses they're going to be affected by the Influenza B virus because that quite often follows A later in the season. That's one possible scenario."
Dr Jennings described the latest patterns as "fascinating". The last time a pattern like this had emerged was in the 1980s.
The viruses depended on which viruses had circulated the year before, he said.
"The main issue is the difference in the viruses circulating and that's a fascinating observation.
"In the South Island last year, we had a significant H3N2 year, in the latter part of our winter we had two peaks, H1N1 and then the H3N2 virus impacted and so that effectively will have primed the [South Island] population and that may be reflected in the dominance of the B virus this year down here," he said.
The H3N2 virus - or Hong Kong virus - first emerged in the pandemic of 1968. Since then it had continued to "quite rapidly evolve", he said.
However, Dr Jennings said there was some good news - all the viruses currently circulating are all covered by this years flu vaccine, available until July 31.
New Zealand has experienced relatively mild winters in the past three years, last experiencing significant peaks in influenza-like illnesses in 2012 and 2010.
When should I see my GP?
Immediately if you're over 65 or pregnant or over 65/under 5 with a history of respiratory conditions. Or, seek help if you can't lift your head off the pillow and are having trouble breathing.
How long are you contagious for once you notice influenza symptoms?
Up to 10 days for children or between three and five days for adults. So if you're sick at work, you're likely spreading it to your colleagues.
How much of the population has taken a flu vaccination so far?
As at 30 June, 1.17 million doses had been handed out, which is about 26 per cent of the population. A total 1.2 million doses were handed out last year.
How do you catch influenza?
Most commonly by air particles, from people sneezing - flu can spread up to two metres away - or not washing their hands.
When will it all end?
Flu season typically lasts until September.
