The medical officer of health for Canterbury says other parts of the country should consider extending the period for free flu vaccinations.
Alistair Humphrey says the number of people suffering from influenza in his region has almost reached its peak, but other areas are a few weeks behind.
Dr Humphrey says increasing numbers are being admitted to Christchurch Hospital, and a special influenza ward has been set up.
He predicts the number of people affected by this year's strain may exceed that of the 2009 swine flu epidemic.
Dr Humphrey says these epidemics last about two months, and while Canterbury is about halfway through, the rest of the country seems to be tracking a couple of weeks behind.
Free vaccinations are available until the end of this month for those aged over 65, and anyone who is pregnant or suffers from a chronic illness.
Dr Humphrey says the Ministry of Health and other district health boards will be considering whether it would be useful to extend that period.
