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.
Vaccination rates
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