"But so far, feedback we've had is a very small proportion of schools reporting any concerns around staffing."
Ardern said about 11 schools in New Zealand had voiced concerns about the mandate's impact on their ability to staff but none said they would need to close.
Tomorrow is the last day for educators to have received at least one dose of the Covid-19 vaccine to keep their classroom jobs.
Ardern said New Zealand's experience in this area reflected what was happening in some countries overseas.
She said many countries had similar requirements, sometimes across an even wider range of employees.
"This is about keeping kids safe."
Ardern said broadly speaking, some employers had asked for clarity on vaccine mandates.
"Where we have applied them we've been very careful," she said. "It is the right thing to do, particularly in healthcare and education."
National's education spokesman Paul Goldsmith said his party had broadly supported the mandate but the Government had done a shambolic job of implementing it.
"What we would have expected is much clearer guidance," he said this morning.
"If you look at each school, every school board of trustees has to go through a very complicated flowchart and at the end it says: 'Get legal advice'. That's no way to run an education system."
Goldsmith said a combination of mandates and returning to school part-time had created a mess.
He said some schools had decided to keep online-only teaching and that was unsatisfactory.
His colleague Simon Bridges was asked about vaccinations and mandates.
"I'm pro-vax. I have some scepticism around the mandates," Bridges said.
"And I do worry that disproportionately those who aren't vaccinated in New Zealand are Māori and Pasifika."
He was asked if he would be comfortable with an unvaccinated teacher teaching his children.
"That raises lots of issues, like for example whether [kids] get vaccinated. In general, if people vaccinate, including kids, I don't know if there's a huge amount to fear."
Bridges said he'd support vaccines for children if the medical authorities here recommended they get vaccinated.
Meanwhile, the New Zealand Disability Support Network (NZDSN) said 237 disability support workers were likely to stay unvaccinated.
More than 200 disabled people were likely to have their support service disrupted as a result of a vaccine mandate, the network's chief executive Peter Reynolds said.
"Not everyone of the 237 is refusing to vaccinate out of protest. Some are seeking medical exemption and a few just haven't got round to it.
"Some are protesting and we expect some of those are likely to vaccinate when they understand this will impact on their job.
"NZDSN members are being encouraged to continue working with staff who may yet vaccinate to get them vaccinated."
Reynolds said people who refused to get vaccinated were putting themselves and others at risk.
"Those who are adamant they will not vaccinate against Covid are being incredibly selfish and short-sighted.
"The impact on staffing arrives at a time when the sector is already struggling with a support worker shortage."
Reynolds said the Ministry of Health had to help the network identify areas where staffing shortages would put disabled people at risk.