United Fire Brigades Association (UFBA) chairman Peter Dunne told Morning Report firefighting ability won't be affected because where numbers are low, FENZ will provide coverage from other areas when needed.
Out of about 11,500 volunteer firefighters nationwide he said there are "probably a few hundred" now unavailable to respond to fires. Where possible they would be transferred to "non-frontline" roles.
In November, the NZ Professional Firefighters Union said the mandate would create "chaos" as some crews already had difficulty staffing their rosters, especially in Auckland and Wellington.
The same month, FENZ confirmed they were seeking fully vaccinated recruits to fill gaps left by those who chose not to get vaccinated, but the training could take months. And that fire crews for Matakana Island in Western Bay of Plenty and Inangahua on the West Coast are unable to respond to calls due to not enough firefighters being vaccinated.
The impact of losing the unvaccinated firefighters comes down to the overall numbers available in each area, Dunne said.
"It depends where they are, in some areas there won't be a problem because there'll be enough other volunteers available to make coverage possible, in some places it may well be that there's a bit of a challenge."
However, it is FENZ's responsibility to make sure enough firefighters are available from wider afield to cover all areas; "which they carry out pretty thoroughly", Dunne said.
"I'm not worried. I think we need to be vigilant, but on the whole we'll see that fire coverage is maintained. It will mean that a good standard of fire cover can be maintained around the country."
Dunne was not aware of any other volunteer fire crews that were unable to respond to fires because they didn't have enough vaccinated crew, and said the Matakana Island and Inangahua crews collectively respond to fewer than 10 fires a year, so the loss was not dramatic.
All firefighters had been asked to get as much information as possible about the vaccine, to help encourage them to get vaccinated, he said.
"We represent volunteers, which means we can't actually tell the volunteers what to do... we merely encourage them to make the right call.
"FENZ and the UFBA have done everything we can to get that message across to our members. It's a matter of more knowledge, more awareness, and general education.
"I think [the numbers vaccinated] are pretty equivalent to the general population. Obviously you'd like to have 100 per cent, but clearly in this environment that's always not going to be possible... this is really the story of the general population, it's not specific to firefighters."
Ministry of Health data showed 92 per cent of New Zealand's population had received two vaccines by Friday.
In a statement FENZ said it was confident in its ability to respond and keep communities safe.
"As an emergency response organisation we always have contingency plans in place so we can respond... on any given day we could get multiple incidents occurring at the same time, that's what we plan for.
"As always, we ask the community to be vigilant with fire safety, make sure your smoke alarms are working and you have an escape plan."
The police service also faces a vaccine deadline, with all constabulary, authorised officers and recruits required to be vaccinated by today.
By the end of last week, 98 per cent of the 10,500 staff in this group within police had received at least one Covid-19 vaccination, leaving more than 200 unvaccinated, with some expected to be stood down.
