New Zealand swine flu cases climbed from 71 to 86 and an Auckland primary school closed as health officials said they remained focused on containment.
There were still relatively few cases and only isolated instances of community transmission, health officials said.
"New Zealand is still in the containment phase," deputy director of public health Fran McGrath said.
"This is the reason that New Zealand has relatively few cases.
"At this time there remains a combination of border management (keep it out) and cluster control (stamp it out)."
The objectives were to prevent, delay and minimise the arrival of further cases of infection into New Zealand, and to control cases or clusters found here.
"This strategy is being kept under continuous review."
Health Minister Tony Ryall said it was important to delay the swine flu peak.
"Normally we'd probably see about 31,000 medical admissions a month into our hospitals during the winter season," he said.
"Officials think that we could end up with another 4000 or so, the swine flu peak matches the winter peak, and that is why we are working assiduously to try and prevent that from happening."
While swine flu has so far proved mild there were fears a second wave of a more serious strain could hit, he told Radio New Zealand.
East Auckland primary school St Patrick's, in Panmure, today sent all of its 145 pupils home.
It has one confirmed case of swine flu, with a number of others suffering flu-like symptoms, principal Carmel Bullot told Radio New Zealand.
About a fifth of the roll was away sick when school started this morning, she said.
"Once school started we found out how many absences we had ... there was a very unusually high number of absences today."
It was decided to close until next Monday and to send a list of sick staff and pupils to health authorities, so they could be contacted.
Other Auckland schools were also hit.
At Kowhai Intermediate, in central city Kingsland, one class of year eight students and a teacher were in quarantine.
Papatoetoe High School in South Auckland has one swine flu case, while on the North Shore at Westlake Girls' High School some 450 year 12 students are away for a week, after one case.
Health Ministry planning was to enable health services to manage large numbers of cases as well as maintain services for those who most need them, Dr McGrath said.
"An important part of this approach will include advising individuals how to look after themselves at home where this is possible -- in the same way they would with seasonal flu."
Swine flu may be serious for some people and they should seek advice either from Healthline 0800 611 116 or their GP -- but phone ahead first.
Of the 86 confirmed cases, 66 are current cases being treated in isolation. There are also 17 probable cases.
The new confirmed cases were: Auckland (two); Rotorua (one); Tauranga (two); in Wellington (five); in Christchurch (five).
The ministry has refined advice to arriving international travellers - only people with flu-like symptoms within four days of travel were now considered to be at risk of swine flu.
Workers should stay home only if they have flu-like symptoms or if they have had medical advice, the ministry said.
They should stay home for seven days after symptoms begin, or until symptom-free for 24 hours, whichever is longer.
This was to keep them from infecting others. Most people would be able to safely recover at home.
Hand hygiene was still the most effective protection - wash hands with soap and water and dry them thoroughly, the ministry advised.
Alcohol-based cleaners were also effective, and people should avoid touching their eyes, nose or mouth, as germs spread this way.
