Waikato District Health Board is considering requiring staff who opt not to have a flu vaccination jab to wear a surgical mask in clinical areas.
The large DHB is consulting over the policy and expects to reach a final decision this week.
Chief executive Nigel Murray said flu was serious and could kill or maim patients. "We don't expect patients to come to hospital and be infected with the flu. That's not what they come for," he said.
"They come to get treated and cared for. So we're going to take every precaution we can, also for our staff who don't want to take the flu home to their family that they might have got off a patient."
Staff at the DHB are being asked to complete a form saying whether they are having the vaccine or not.
There are also volunteer "influenza champions" who are credited with lifting vaccination rates among staff from 47 percent to 53 percent. A weekly prize draw is also being held to boost staff vaccination against flu.
Dr Murray said no-one was being forced to have the free jab. "We are not forcing the flu injection, or jab as we call it, we are acting to put personal protective equipment, which is a simple surgical mask on our staff to protect them and their patients and their families from transmitting the flu."
The move follows a similar one in British Columbia, in Canada - including at Fraser Health, where Dr Murray was chief executive until the middle of last year.
Canterbury virologist Lance Jennings said it was a sensible approach for health workers, who were three times more likely to get flu than others.
"This policy there [British Columbia] has survived intensive court challenges by labour organisations and has led to an increase in vaccine coverage amongst healthcare workers from up to 80 percent - 86 percent - in the second year that this programme has been running."
Dr Jennings said staff did not enjoy wearing a mask, and that was why it lifted immunisation rates.
"Staff have got sick of wearing a mask very rapidly and have decided to receive an influenza vaccine, and this has led to the increased coverage," he said.
Union warns of backlash
Nurses Organisation industrial adviser Lesley Harry said it was keen to work with DHBs to encourage nurses to have the flu jab - which most do - but believed that requiring those who chose not to have the jab to wear a mask was impractical.
"The individual will be exposed, the patients will be curious as to why a particular nurse or midwife is required to wear a mask. But that hasn't happened yet and if it happens we'll look at it more closely. In the meantime we'll be submitting to the DHB that that's just unpractical."
She said taking a more punitive approach would be likely to provoke a backlash, which would be counterproductive.
The Auckland DHB also asks staff whether they have been vaccinated or not, and questions those who opt against the flu jab about the reason for that decision.
Its chief medical officer, Margaret Wilsher, said staff who chose not to get vaccinated were asked to consider wearing a surgical mask when treating high-risk patients during any flu epidemic.
"We'd rather take a line of encouragement and positive response than one of directing staff," she said.
"However we are mindful of the fact that we have some very vulnerable patients in our organisation, such as those with advanced cancer on chemotherapy or who are immunosuppressed for other reasons."
Non-immunised staff members caring for particularly vulnerable patients would be asked to wear a mask.
Dr Wilsher said an encouraging approach had lifted immunisation against flu among clinical staff from under 50 in one large professional grouping to 75 percent last year.
"Our duty of care is to our patients and if we can enable staff to continue to care even whilst wearing a mask then so be it. But if not, we may look to roster staff who have been vaccinated."
Wider vaccine offered
Auckland and Wellington's Capital and Coast DHB are among those offering their staff the regular three-strain or trivalent vaccine - the vaccine approved by the World Health Organisation and being rolled out to New Zealanders this flu season.
Some DHBs, including Waikato and Canterbury, have bought supplies or a quadravalent vaccine, covering three equivalent strains but with an extra flu strain offering wider coverage.
Waikato's Dr Nigel Murray said in a tertiary hospital like his it was very important to keep the circulation of flu to an absolute minimum.
"We wanted to protect our staff, we wanted to protect our patients and the quadravalent vaccine offers an increased level of protection."
Dr Jennings said it would not be known if that vaccine was more effective than the three-strain one until the flu season began.
Flu vaccines are several weeks' late being rolled out after a tough northern hemisphere flu season prompted international health officials to add two new strains to the southern hemisphere vaccine to boost its effectiveness.