The swine flu pandemic is expected to last between 18 and 24 months and could affect up to one million people in New Zealand.
The pandemic could last up to two years and see 30 percent of the population - around a million people - infected.
All of the swine flu cases in New Zealand had come from people who had either come into the country from overseas, or were contracted by people in close contact with travellers who had been abroad, Dr Bloomfield said.
Meanwhile, Auckland Hospital was on high alert and a child centre had closed after a nurse and her child tested positive for swine flu after returning to the country from a family holiday in the United Kingdom on Saturday.
Seasonal flu hits up to 20 percent, about 760,000 New Zealanders each year. On average, 2.7 percent of the population (156,000 people) will go to their GP because of flu each year and an estimated 95 people will die.
