The Canterbury Medical Officer of Health says extending free influenza jabs to those under 18 appears to have paid off, with a drop in the number of hospital admissions.
Alistair Humphrey says in the year to the end of June, 56 people were admitted to hospital with an influenza-like illness, down from 132 the previous year.
Free flu shots are offered to people over 65, pregnant women and those with chronic illnesses.
After the Canterbury earthquakes, that was extended to under 18s to limit transmission of flu between schoolchildren.
Dr Humphrey says about 18% of that age group has been vaccinated and 31% of the total population.
He says that's the highest flu vaccination rate in the country, and the region has one of the lowest rates of influenza this year.