Three of the workers were suspended and given an opportunity to "review the clinical evidence" and meet their supervisors about the issue, the DHB said. All had since returned to work. The fourth staffer was made subject to "restrictions".
The DHB refused to say last night how long the workers were suspended or whether they agreed to vaccinations in order to return to work.
While no staff have yet taken legal action over the policy, the DHB has been served with a claim by several unions challenging it.
A DHB spokesman reiterated that any staff who worked in clinical areas and were not prepared to be immunised or wear a mask would be removed from active clinical duty.
"If following further discussion a solution is not reached, then it is foreseeable that employment will be terminated."
One staff member told the Weekend Herald that while she personally didn't have an issue with the policy, some staff had been "very vocal", protesting it was bullying behaviour.
The DHB, however, claimed the policy had had "widespread acceptance" and contributed to a big increase in staff getting vaccinated.
More than 75 per cent had - an improvement on last year's 53 per cent.
"When considering that our employee numbers are in excess of 6,500, the reality is that almost all staff are getting on with doing their duties and they recognise that the intent of the policy is to provide a safer clinical environment for our patients and fellow employees," the spokesman said.
But the Nurses Organisation sees the measure as a "punitive action" against staff, some of whom have turned to the union for support.
"Whether the DHB can legally suspend staff and discipline them is unknown," said the union's industrial adviser, Lesley Harry. "However, we believe the DHB has failed in its obligations to adequately consult with unions both in respect of the implementation of the policy and its impact on the workforce."
Ms Harry said that while the Nurses Organisation supported education on vaccination, as well as making jabs readily available to staff, Waikato DHB had gone too far.
"We think forcing healthy nurses to wear masks when dealing with patients and their families regardless of circumstances is bullying behaviour," she said.
"It doesn't make sense to suspend a nurse, send her or him home and leave the work area short staffed and unsafe for patients."
The Public Service Association also condemned the policy, calling it the "latest from employers who do not listen to their staff and prefer using the stick over the carrot".
And the executive director of the Association of Salaried Medical Specialists, Ian Powell, was concerned the policy could lead to "naming, shaming and blaming" of unvaccinated staff.
The office of Health Minister Jonathan Coleman said he could not comment on what was an operational matter for the DHB.
More than 1.2 million influenza vaccinations have been administered as the illness soars to epidemic levels, similar to the situation in 2010 and 2012, when some patients died.
The last weekly influenza report from ESR shows 319 suspected cases were reported in the week to Sunday, up from 184 in the previous week.
