Free flu jabs were shunned by more than half the staff offered them at district health boards this year, prompting fears that vulnerable patients are being put at risk.
Only a third of midwives accepted the vaccination and just over half of doctors.
In the upper North Island, the highest overall rate was 54 per cent, at the Auckland District Health Board; Waitemata was lowest at 40 per cent. Counties Manukau was at 45 per cent and Waikato 44 per cent. The highest rate nationally was Canterbury's 62 per cent.
The national average was 46 per cent among most health occupational groups, although some health boards did not offer free jabs to all groups.
This is higher than rates of 20 to 40 per cent cited in a New Zealand Medical Journal article in 2007 which called for mandatory annual flu vaccination for all frontline health workers unless they had medical reasons not to have the injection.
GP Dr Nikki Turner, director of the Immunisation Advisory Centre at Auckland University, said: "We clearly still have a problem with health professionals in secondary services not having high rates of vaccination when they potentially could be spreading flu to vulnerable people.
"The main risk is that when they are incubating influenza, even before they know they have got it, they could be spreading it to patients ... a lot of people continue to work even when they are still a little bit unwell and could be spreading the flu."
Higher rates were needed, particularly among those who worked with the elderly, people with chronic diseases or children under 1.
"Flu vaccination is not just for individual protection."
Dr Turner said previous research had shown that health practitioners, like the general population, were influenced by vaccination myths, although to a lesser extent.
The main myth was that the vaccine could cause influenza.
"It just can't, because it's not the full virus. People get other ... viral infections and assume that the vaccine didn't work, because they call them 'flu'."
The Health Ministry's chief medical officer, Dr Don Mackie, said there had been some improvement in vaccination rates but more was needed.
Uptake of free influenza vaccination by district health board staff:
Nurses: 42 per cent
Doctors: 53 per cent
Midwives: 33 per cent
Source: Ministry of Health