The Government has issued a strongly worded "recommendation" to schools to enforce mask-wearing for the first four weeks of Term 3.

But it's still stopped short of making masks compulsory nationally, instead leaving it to each school to decide for itself.

That stronger wording comes as the Omicron wave appears to have reached a peak of just over 10,000 daily cases. Covid has killed or hastened the deaths of at least 1252 people in New Zealand, most of them this year.

While daily cases have now dipped below 10,000, it's not clear how much the school holidays have slowed transmission - and whether cases will rise again when students are back in the classroom.

A newsletter sent to all schools last night said both the Education and Health Ministries were recommending students Year 4 and up should wear masks for the next four weeks, while indoors and where it won't have a "significant impact on teaching and learning".

It said Associate Education Minister Jan Tinetti had also written to school boards, outlining the Government's "strong recommendation to review and enforce a mask-wearing policy as much as practicable".

The Herald is aware of a number of school boards that have since contacted parents to let them know masks will be compulsory from Monday.

Associate Minister of Education Jan Tinetti has written to school boards asking them to enforce a mask wearing policy for the first four weeks of Term 3. Photo / Sylvie Whinray

Newmarket Primary principal Dr Wendy Kofoed welcomed the stronger wording from the ministry, calling masking in schools a "no-brainer".

Kofoed, who is president of the Auckland Primary Principals' Association, said many schools in the city had continued with masks throughout the orange setting. At Newmarket all students from Year 1 wear masks, a policy with strong support from parents.

"That's just part of our culture ... and is one of the reasons, I think, that we've managed to keep the school open. While we've had some rolling cases of Covid, we've been able to staff the classrooms and to maintain programmes."

She believed the Education Ministry was doing everything it could to get schools to enforce masking, including supplying them with masks.

"It would be the politicians that would have to mandate or make a stronger recommendation, I would imagine."

Dr Wendy Kofoed, president of the Auckland Primary Principals' Association, says masking at schools is a "no-brainer". Photo / Supplied

Earlier this week Dr Ashley Bloomfield called for schools to bring back mask wearing, saying those with masking in place had been able to minimise infection.

But when asked if the mask requirement should be compulsory, he said the latest advice from Ministry of Health officials was that the current setting was appropriate.

Under the red light setting, masks were compulsory in schools for Years 4 and up. But since the move to orange in April each school board has set its own mask policy, a change criticised by public health experts.

It meant some schools enforced masks while others only encouraged them - despite a wave of winter illness causing staff shortages and student absences that forced many schools to return to hybrid or online learning.

'What gets measured, gets done' - public health expert

Otago University epidemiologist Professor Michael Baker wants the Ministry of Education to ask schools whether they have enforced mask-wearing. Photo / Supplied

Otago University epidemiologist Professor Michael Baker said the wording from the ministry was "pretty strong"; the next step was to ask schools whether they were following the recommendation.

"Otherwise, we don't know how the policy is being rolled out - it's that classic thing of what gets measured, gets done," he said.

"It's really positive that they're recognising that schools are an important site for transmission. That is how the virus will be leaping from household to household.

"The school environment meets all the criteria for being a high transmission setting, [when we] think about the three Cs of confined, close contact and crowded."

Masks were "phenomenally effective" at cutting transmission, he said - if everyone was wearing a mask it could reduce the risk of an infected person spreading the virus up to 75-fold. But that required people to wear the right type of mask, and to wear it properly.

"We need people going and observing behaviour across schools and different age groups to see what kind of masks are people using, how are they wearing them? Are they wearing them consistently? Because there's no point in having policies unless we're actually monitoring them."

Ministry of Education aiming for 'balance' between masks and education

Last night's bulletin highlighted the struggles schools faced last term, and said illness was "likely to put more pressure on your school, kura and community".

It acknowledged some schools may find enforcing masks challenging, but asked them to "take action to strengthen your mask-wearing policy as soon as possible".

There could be situations where masks weren't practical - such as playing indoor sport, singing or drama, or playing musical instruments - in which case ventilation and physical distancing should be prioritised.

"This approach attempts to balance the benefits of mask-wearing with the primary purpose of school's education across curriculum areas and ensure students with particular learning needs that may be hindered by mask-wearing are considered," it said.

The ministry would later advise whether masking policies should be extended beyond the first four weeks of term.