Data collected by the Institute of Environmental Science and Research (ESR) in the Auckland and Counties Manukau health districts last year shows school-aged children and teenagers had by far the highest rate of lab-confirmed flu among GP patients.
Experts believe this in part reflects the nature of the classroom as an ideal spreader of viruses because of poor cough and sneeze hygiene and close contact.
"Children gather in the classroom and often share the virus quite a lot," says Dr Sue Huang, a virologist and head of ESR's national flu centre.
Flu viruses are transmitted within coughed-out and sneezed-out droplets which are inhaled by others or picked up from objects by our fingers and transferred to our mouths, noses or eyes. They get into cells, which they hijack and destroy in the process of producing vast quantities of new influenza viruses.
But Dr Huang says last year's flu data was influenced by the dominance of B-strain virus, often linked "with high incidence in school-aged children in the community".
Last year was a "moderate" flu season for New Zealand. During the peak week, in August, about 160 people in every 100,000 enrolled patients went to a GP for flu-like illness.
That was higher than the two preceding years (which peaked at about 130 and 90 a week), but much lower than in the 2009 A-strain H1N1 flu pandemic, when about 280 visits per 100,000 patients were recorded in the peak week, in July.
Ms Oliver's year-2 class have quickly adopted the safe-sneeze message and almost flawlessly demonstrated it for the Herald in a lesson that used a water-spray bottle, blown bubbles and handshakes with moistened glitter.
Until July 31, flu shots are state-funded for people 65 or older, pregnant women, and others aged over 6 months with certain pre-existing health problems.
How to avoid influenza
• Clean hands regularly
• Avoid touching your eyes, nose and mouth
• Don't share drinks
• Avoid crowded places
• Have the annual influenza vaccination
