The absences have hit in the past few weeks as symptoms of flu-like illnesses persist later into the year than usual.
Southland Boys’ High School rostered its year 11-13 students home because a significant number of staff were affected by winter illness and there was a shortage of available relief staff.
The school said the decision was not made lightly.
Its priority was to ensure a safe and supportive learning environment and it was unable to so with its current staffing constraints, it said.
Green Island School principal Aaron Warrington said he had noticed many pupils and staff with the flu.
Some had been sick for about a week at a time.
He said there was a noticeable impact on numbers at the school.
There was more of an impact than last year.
Otago Primary Principals’ Association chairwoman Kim Blackwood said term 3 was always the term with high absences due to sickness.
"Typical coughs and colds alongside tummy bugs are prevalent currently".
However, it was no worse than term 3 in other years.
University of Otago department of biochemistry professor Kurt Krause said while it was true there was a spike in flu-like illnesses in winter every year, this year the peak number of people reporting sickness was delayed. The Public Health and Forensic Science respiratory illness dashboard showed community influenza-like illnesses were peaking later this year, in August and September.
However, hospitalisation rates had dropped for severe acute respiratory infections.
A new vaccine for influenza was formulated every year based on what viruses were seen around the world, Prof Krause said.
If the vaccine strain was different from what was circulating in the community then the vaccine would be less effective.
The winter peak for flu usually lasted about four months and was expected to end in late September.
"As winter wanes, it starts getting better and better."
