As Queensland's horror flu season shows no sign of abating, one Brisbane school has been grappling with an average of 300 absences a day - reaching as high as 420.
A significant number of absentees were recorded at Marist Brothers College Ashgrove, with an average of 300 absences a day, the "vast majority" flu-related.
The number of pupils away from school soared to 420 absentees on Wednesday - one-quarter of the 1632-strong student population.
This week Fortitude Valley's Queensland Music Industry College was forced to cancel all classes on Monday, leaving only self-directed study available for its 90 students, as eight of the 10 teachers were too unwell to work with flu-related illness.
Health experts have warned this year's flu season is expected to hit hard, and latest Queensland Health data shows more than 16,000 laboratory confirmed cases of influenza so far this year, four times the average rate for the past four years.
At least 25 Queenslanders have this year died from the flu, with experts predicting the peak of the season may be still to come.
Marist Brothers College Ashgrove headmaster Peter McLoughlin said it was a significant illness that had caused the vast majority of the abnormal absence, causing a "pretty big impact on the school community".
The best attendance rate was recorded on Friday, with 270 pupils or a sixth of the school still absent.
"When you're ill like that you need to stay home," Mr McLoughlin said.
"Most days last week we had in excess of 20 teachers away, it was a big, big undertaking for sure.
"We weren't even looking at the statistics last year so that will give you an idea of how significant it was."
The outbreak could not have come at a worse time, just two weeks before holidays and with Year 12 pupils facing exams.
"It will impact some students, and boys are looking at illness and misadventure with exams, but dealing with by a case-by-case basis," Mr McLoughlin said.
He said the school had installed "a lot more" hand sanitiser dispensers over the past few weeks to combat the virus, and communicated relevant public health information to the school community.
Immunisation Coalition Professor Robert Booy said the influenza season could still peak in June and July, and the nationwide problem could have attack rates in schools of up to 30 per cent.
"A lot of students can be affected and we've seen the same thing in schools in other parts of Australia; influenza can affect preschool and schoolchildren quite severely," he said.
Professor Booy urged people to use disposable tissues, cough sneeze into the crook of their arm, and students with any symptoms should stay at home to help prevent spreading the flu.
"There's a major ripple effect where students bring it home, infect Mum and Dad, they get unwell and then grandparents step into care and they get sick," he said.
"It's not too late to get vaccinated, there's still more influenza that's going to affect the community in the next month."
The Education Department said yesterday it did not have access to real time absentee data so could not say how many of its schools had been hit hard by illness this winter.