Thousands more children are going to school each day as Covid-19 case numbers drop.

Principals had worried August would be the worst period for winter illnesses but Education Ministry figures showed attendance averaged 82.5 per cent for the first four weeks of the current school term, an improvement on 79 per cent for the last five weeks of the second school term.

That equated to about 38,000 more children in class each day.

Canterbury Primary Principals Association president and Beckenham Te Kura o Pūroto principal Sandy Hastings says Covid-19 cases at her school have fallen away.

"We've got nobody in our school at the moment that we're aware of with Covid, so that's a real positive and it's been like that more or less for about three weeks now and that's the first time since March that we've been in that situation," she says.

"Illnesses among staff are still high, among students not quite so much. We've got 90 per cent of our kids here this morning and that's really good and that's better than it was through Covid, we were down to about 76 to 80 per cent."

Wearing facemasks has made a real difference in preventing the spread of respiratory illnesses in classrooms, she says.

But staff are still getting ill or having to stay home with sick children and finding relief teachers to cover for them has become a lot more difficult, she says.

"Up until now in our school we haven't had days where we haven't been able to get a reliever if we've needed one and in the last three weeks we've had three or four days where we haven't been able to get a reliever so that's a new situation for us."

Sandy says it's likely some relief teachers are no longer available because they have taken full-time jobs to help schools cope with new enrolments by five-year-olds.

Other, older teachers have stopped relief teaching because they are worried about catching Covid-19.

In Northland, Tai Tokerau Principals Association president Pat Newman says more children are back in class but staff absences are the worst he has ever seen.

He says if teachers called in sick and there are no relief teachers available, some classes have to double-up.

"Staff-wise it's diabolical.

"It's worse this term for staffing than I've ever known it in my whole 40 years as a principal and that includes last term. So many of our relievers were either sucked up with the Covid stuff and then what's left has been caught up with the illnesses and been pulled into schools as permanent [teachers] so there's a real shortage of relievers out there."

In Auckland, Ōtāhuhu College principal Neil Watson says attendance is still below pre-pandemic levels but has definitely improved since term two.

"This term we've seen a steady increase of students coming back to school and for some of them the first time in a long time attending at school and we're really pleased with that."

Watson says staff absences have also reduced a lot since last term, but are still relatively high compared to pre-pandemic years.

"What we're seeing with absence patterns is a degree of the usual winter illness, probably down but the issue is the isolation period, seven days as opposed to what would normally two or three days for flu, or even pre-pandemic staff would turn up with a bit of a flu and they'll soldier on for the day but those days are gone," he says.

-RNZ/John Gerritsen.