The number of confirmed cases of Influenza A/H1N1 rose to 653 on Tuesday, up 64 from 589 on Monday, Xinhua reported.
The Ministry of Health said Wellington still has most cases, at 209; followed by Canterbury on 183 and Auckland on 176.
A woman in her early 20s was in a critical condition in intensive care in Hawke's Bay Regional Hospital. Another woman was critical but stable in Wellington Hospital.
Health officials said the virus is expected to cause many more infections than are seen with seasonal or winter flu because most people have no or little immunity to it, and infections can be expected to continue for months yet. So far, most of the people contracting the virus are experiencing relatively mild to moderate symptoms.