Primary schools across the country are reporting up to half of their pupils off sick after being struck down by highly contagious respiratory illnesses and other bugs.
Babies, toddlers and preschoolers were also being hit hard by the latest spate of illness with some Auckland kindergartens reporting up to a fifth of kids being home unwell.
Primary school rolls had slumped drastically in urban settings with attendance down between 10 and 50 per cent due to respiratory illnesses and in some cases a tummy bug, New Zealand Principal's Federation principal Perry Rush said.
Attendance levels also tended to drop off during the final week of a term, he said.
Poroutawhao School in Palmerston North had 45 of its 112 students off sick this week, said Auckland Primary School Association president Stephen Lethbridge.
He said there had been a lot of discussion among principals about RSV and it was important the public took hand-washing and staying home if sick, seriously.
The latest attendance information available from the Ministry of Education shows the average attendance rate for both primary and secondary schools in week eight was at 88 per cent nationally, just less than 1 per cent lower than the same time last year.
The more drastic drop in attendance is likely to show in last week's figures which won't be released until Thursday morning.
While schools were well placed to deal with illness, it was harder to get relieving staff so the school holidays starting next week couldn't have come at a better time and should also provide a natural break to any further spread, Rush said.
Auckland Kindergarten Association general manager of education and innovation Bram Kukler said last week they saw an increase of between 15 and 20 per cent of its mainly 3 to 5-year-olds off sick from its 107 kindergartens and four KiNZ centres, including a number of confirmed RSV cases.
"In the best interests of tamariki, we advise parents and whānau to keep their children home if they are unwell, and staff to stay home if they are sick."
Southern District Health Board also reported seeing sick children leading to absences at Kōhunga Reo and early childhood centres across the district.
"It is difficult to gauge how this season of viral infections will evolve. In Southern we tend to have a wave of presentations that occurs after those in the North Island.
"Generally, August and September are our busiest months for RSV and respiratory infections," Dr Nigel Millar, Southern DHB's chief medical officer, said.
BestStart Educare deputy chief executive Fiona Hughes said they were also seeing an increase of preschoolers, toddlers and babies absent due to illnesses from its centres at the moment.
Hughes has written to parents urging them to adopt good hygiene practices, including vigilant hand washing to try and prevent the spread.
In her note, sighted by the Herald, Hughes said they were aware of children becoming unwell, attending the centre and infecting others.
"We know this worries parents. We know how much parents value good health for their child. We also know how disruptive it is to working parents having to take time off to care for an unwell child," she said.
"A year ago, we were all very diligent with our hand-washing practices. As winter sets in and we are exposed to more virus outbreaks, we encourage our parents to think about hand hygiene as if it was a year ago."
This included also encouraging children to wash their hands at home and getting older children to wash their hands before touching a baby at home.
She also reminded parents to keep children home if they were unwell.
NZ Kindergarten Association chief executive Jill Bond said their kindergartens - scattered around the North and South Islands - didn't appear to have been adversely impacted by RSV.
"It's not any different from normal ups and downs of attendance. Kids come down with flus and things happen in their families that cause them to be absent, but the trends that we are seeing are consistent with where they have been previously."
Last week Auckland Regional Public Health wrote to all early learning centres advising them about the number of preschoolers and some childcare staff in the region unwell with coughs and colds.
It warned many of the symptoms were similar to Covid-19 and that adults with the virus symptoms should be tested. However, it was not always necessary for children aged under 11 years old to be tested.