The Government has widened the powers of health officials to order people into quarantine to control the spread of swine flu.
Health Minister Tony Ryall announced last night that "non-seasonal influenza" - swine flu - had been added to health regulations covering infectious and notifiable diseases.
This gives medical officers of health the power to order people to be quarantined at home if they have been in close contact with someone who has swine flu.
This includes barring children and teachers from schools.
The move follows the addition of swine flu to the Health Act on April 29. That gave medical officers of health the power to enforce isolation of swine flu cases at the border and in the community - and to quarantine suspect cases at the border, but not in the wider community.
These powers have not needed to be used because everybody who has been asked to isolate themselves has done so voluntarily.
Before each of the legal amendments, medical officers of health could have asked the minister to give them the power to enforce isolation if someone had refused to be isolated.
"This is purely a precautionary step," Mr Ryall said last night.
"Our experience is that all affected New Zealanders have been fully co-operative in isolating themselves.
"This regulation does not allow for total school closures, which can be invoked only with an authorisation of special powers by the Minister of Health, or if an epidemic notice [issued by the Prime Minister] is in force. No such notice is in force."
Other diseases covered by the regulations include Sars, hepatitis B and whooping cough.
The Ministry of Health said yesterday that New Zealand's tally of confirmed cases was 17.
More than 1000 cases have been reported in Australia, and around the world the total is more than 21,000.
This includes 125 deaths.
Schools are concerned that they have not been given enough information to advise parents of the wider effect of closing to prevent the spread of swine flu.
The ministry has told schools to be prepared for sudden closures that could last several weeks, and to talk to parents about remote learning.
But schools say they have not been advised how families could manage if their child was quarantined.
Rangitoto College principal David Hodge said he learned how disruptive quarantine was when 22 students and three staff and their families were placed in isolation after going on the school's Spanish language trip to Mexico.
Closing Rangitoto - a college of 3100 students in Mairangi Bay, North Shore City - could put the whole community in turmoil.
He said the school was confident in its communication channels, and would be able to send work to students through the internet.
But it had not had been told if a school closure would apply to staff as well as students.
Gladstone Primary principal Dave Shadbolt sent the pandemic plan of his Mt Albert school to parents yesterday.
Most of the advice was about general hygiene, he said, and staff were reminding students about hand-washing routines and covering mouths and noses when they sneezed.
Mr Shadbolt said he assumed families in which both parents worked would have to organise care if the school closed.
The manager of occupational health and safety for the Employers and Manufacturers Association Northern, Paul Jarvie, said the effect of widespread quarantine caused by swine flu would compound on the impact of the recession, especially for workplaces already operating with skeleton crews.
The greatest cost to companies would mostly be loss of productivity, because if an employee had used up annual sick and holiday leave entitlements, an employer did not legally have to pay them.
The national commissioner of Work and Income, Liz Jones, said: "People facing difficulties in special circumstances such as an outbreak of [swine flu] may be eligible for assistance if they do not have access to other resources or support."