A fifth New Zealand case of the coronavirus COVID-19 has been confirmed, Ministry of Health officials said on Saturday afternoon.

She is a woman in her 40s, and is the partner of third confirmed case.

"This is fitting the pattern of existing spread primarily within families," said Director-General of Health Ashley Bloomfield.

"Most human-to-human transmission is happening inside families," he said, "in that close household setting. Casual contact tracing is underway for that individual, and the close contacts are already in self-isolation."

The woman is also in self-isolation, and Dr Bloomfield said neither she or her family require hospital care.

New Zealand's first case of the disease sweeping the globe was confirmed in late February. According to the World Health Organization, there have now been 101,800 cases confirmed and 3460 deaths. No deaths have been reported in New Zealand yet.

Of the eight Kiwis who were on board the now-quarantined cruise ship Grand Princess off the coast of San Francisco in February, five are well and outside the 14-day period where symptoms would show if they were infected.

One is a woman in her 70s who was earlier in hospital with a respiratory illness. She recovered, but then was readmitted to North Shore Hospital with an unrelated condition.

"She has now been tested and although the test results came back negative, we have a strong consensus... that when she was first admitted with the respiratory illness, she was a probable case."