The seasonal vaccine is altered most years to cover the strains of the virus that are circulating at the time.
Deputy director of public health Dr Shirley Crawshaw said about 1.2 million doses of the vaccine were expected to be distributed, based on the last few years.
The virus, which infects the respiratory system, can affect anyone, but particularly the young, elderly, pregnant or people with compromised immune systems.
Spread by coughing, sneezing and through direct contact, it is very easy to catch.
While a cold was short-lived and mild, the flu was characterised by a high fever, severe headache, cough, aches, shivering and often required bed rest, or hospitalisation in more serious cases.
Immunisation is free for those considered at higher risk of contracting the virus until the end of July. Health officials recommend those who are in close contact with these groups should also be vaccinated.
Dr Crawshaw said individual practices and pharmacies set their own charges and the vaccine typically costs between $25 and $40.
The vaccine is usually given as one dose a year, though children being immunised for the first time receive two a month apart. It takes about two weeks to be effective, and could significantly reduce the incidence of the disease and time off work.
The Immunisation Advisory Centre estimates about 200,000 people contract influenza each year. The Institute of Environmental Science and Research estimated that last year 49,821 New Zealanders, or 1.1 per cent of the population, visited a doctor for a flu-like illness.
Figures from the Ministry of Health show 16 people died from influenza in 2013, a decrease from 42 in 2012. Data from the last two years is not yet available.
Number of Kiwis to visit GP with an influenza-like virus:
2015: 49,821
2014: 29,768
2013: 25,598
2012: 48,186
Source: Institute of Environmental and Scientific Research
