As flu season approaches, experts are warning a particularly nasty strain of the virus is headed our way.
The northern hemisphere has been hit hard by influenza this winter, and vaccinations have been either "mediocre or not effective" against some strains of the virus, according to Associate Professor Nikki Turner, director of the National Immunisation Advisory Centre.
To combat this, for the first time in New Zealand, Government-funded vaccines will be "quadrivalent", meaning they inoculate against four separate strains of the virus to offer broader protection.
More than 1 million New Zealanders receive an influenza vaccine each year. It's free for people over 65, for pregnant women, and for people with chronic conditions like asthma, heart disease and diabetes.
Last year was a fairly mild flu season for New Zealand, peaking at about 50 GP visits for influenza-like illness for every 100,000 people per week. This compares to the 2009 influenza pandemic, which peaked at over 250 cases per 100,000.
But Professor Turner says determining the overall number of people infected each season is difficult.
"Research shows about one in four people may be infected with influenza during a moderate flu season, and the majority of those people may not know they have flu. This is one reason why immunisation is a key line of defence."
It's difficult to determine the number of deaths caused by influenza each year, as the cause of death can be attributed to something else that was complicated by the virus.
Professor Turner says the "Holy Grail" of flu vaccines would be one that covered all strains and wouldn't need to be changed every season.
In the meantime, though: "We are stuck with imperfect vaccines that are still important to use against such a nasty and common virus."
Watch Newshub Nation 9:30am Saturday/10am Sunday on TV3, and follow us on Facebook and Twitter.
Newshub Nation is supported by NZ On Air.