She was already in quarantine in the Chateau on the Park in Christchurch after a family member tested positive from a day three test. The woman remains in quarantine.
Today's three new cases take New Zealand's total to 1203.
None of the current patients require hospital-level care.
"Yesterday our laboratories completed 1365 tests. Our seven-day rolling daily average number of tests is 1984," the ministry said.
The total number of tests completed in New Zealand to date is 442,488.
Yesterday there was one new case of Covid-19 in managed isolation in New Zealand.
The case was a man in his 50s who arrived in the country on July 12 from Central Africa via Tanzania, Doha and Brisbane.
He is now in an Auckland quarantine facility.
Earlier today the National Party unveiled new policy stating that anyone entering New Zealand from October 3 would be charged a $3000 fee per adult for their managed isolation if National wins the election.
The party's Covid-19 Border Response spokesman Gerry Brownlee said the fee would be used "partially meet the costs of their quarantine".
Each adult would be required to pay $3000 per adult towards the cost.
Additional adults in a room if a couple had arrived would be charged an additional $1000. Children under 3 would have no cost and over 3s would incur an additional $500.
"Currently taxpayers are funding a long and very expensive government response to let people come into the country. It's entirely fair that those who benefit pay a share," he said.
"This fee is for the purpose of cost recovery to reduce the burden on New Zealand taxpayers, and to cover some of the costs of accommodation and food over the 14 days of required quarantine for persons entering the country."
Brownlee said there could be exemptions on compassionate grounds, but only for New Zealand citizens and permanent residents.
National's policy was similar to that in New South Wales, Queensland and South Australia, he said.
