Health officials can order people into quarantine after the Government passed new regulations to combat swine flu.
The virus was today added to the Health (Infectious and Notifiable Diseases) Regulations, created in 1966.
"This gives medical officers of health legal powers, if needed, to require people to isolate themselves at home and to exclude children and teachers from school if they have swine flu or are in close contact with someone with swine flu," Health Minister Tony Ryall said.
Confirmed cases in New Zealand today reached 17, up from 14 yesterday.
A Canterbury man yesterday became the South Island's first confirmed case after returning from Los Angeles on Air New Zealand flight NZ5 on May 31.
His seven-year-old son today tested positive for the H1N1 virus as did a second passenger from the flight.
The third case confirmed today was a passenger from Air New Zealand flight NZ124, which arrived from Melbourne on June 5.
There are also 103 suspected cases, up from 92 yesterday, with 10 deemed "probable".
Mr Ryall said the medical officers' new powers did not extend to the closure of schools.
"(That) can only be invoked by the minister of health, or if an epidemic notice is in force."
However, a n Auckland childcare centre shut its doors this week after a one-year-old at the centre tested positive on Friday, having recently returned from Melbourne.
Children and staff at Tama Ale Eleele A'oga Amata childcare centre have all tested negative for swine flu, but will keep themselves in isolation until Thursday.
Jenny Yule, managing director of in-home childcare provider Porse, said since the child was diagnosed the company had experienced a "surge of phone calls" from parents.
Health authorities have warned swine flu will continue to spread, mirroring Australia where confirmed cases today jumped to 1051, up from 876 on Friday.
Health Ministry director of public health Mark Jacobs told family doctors community transmission in New Zealand was inevitable.
"The recent rapid increase in cases in Australia in particular emphasises that community transmission in New Zealand is a matter of when rather than if," he wrote in the College of GPs newsletter, ePulse.
"In the event of sustained community transmission, hospitals already entering the seasonal influenza period would soon be overwhelmed, most people will need to be cared for at home supported by telephone triage, probably through Healthline."
Canterbury Medical Officer of Health Dr Alistair Humphrey agreed with Dr Jacobs.
"Australia went from nothing to basically losing control of the outbreak in a week. That has happened in quite a few countries but it hasn't happened yet in New Zealand.
"By and large we've done a good job at keeping it at bay; we don't have thousands of cases all occurring at one go putting our health services and indeed our businesses under stress."
As at 6pm yesterday the World Health Organisation reported 21,940 cases in 69 countries, with 125 deaths.
