The new case is the older sibling of a Papatoetoe High School student who was a casual-plus contact.
The student had returned three recent negative tests and is asymptomatic. As a result, officials are carrying out interviews to work out how this new case was infected.
"Case M developed symptoms on Tuesday 23 February. As a result, the person is regarded as being potentially infectious from Sunday 21 February," the MoH says.
"Testing of the household of five is underway. Test results for the other family members are expected this evening."
There are a number of locations of interest, which the MoH will be updating progressively on its website this evening.
"The Ministry's website will also include advice on what to do if you were at any of these locations at the time when you could potentially have been exposed," the MoH says.
"Please only call Healthline if you were potentially exposed."
The locations of interest are below:
- Hunter Plaza (26 February)
- Burger King Highland Park (25 February)
- Your Health Pharmacy (23 February)
- Pak n Save Manakau (21 February)