She has not been at school, but was a casual plus contact of the first Papatoetoe High School case from the February cluster and had been advised to self-isolate and get tested.
The other confirmed case, known as Case K, was an infant, who didn't have childcare outside the home, the ministry said.
The teenage sibling, known as Case J, recently finished school and has been working at Kmart Botany, the ministry said.
Case J was at work on Friday February 19 and Saturday February 20 between 4pm and 10pm. Kmart Botany is regarded as a location of interest.
"Therefore anyone who was at Kmart Botany, 500 Ti Rakau Drive, Botany Downs, at these times is considered a casual plus contact.
"If you are a casual plus contact, you are advised to immediately isolate at home and call Healthline on 0800 358 5453 for advice on isolation timeframes and testing requirements.
"Thirty-one staff at Kmart have already been identified as close contacts and are isolating and being provided with public health advice."
A Kmart spokeswoman said the health and safety of its staff and customers was its highest priority.
"We can confirm that we were alerted this afternoon of a team member who has returned a positive result for Covid-19 at the Kmart Botany store," she said.
"As soon as we were made aware, we immediately closed the store as a safety precaution and commenced a thorough sanitisation of the store."
"We have also asked all contacts of this team member to isolate. We are working closely with the New Zealand Department of Health and will continue to take every safety precaution."
The other location of interest is Dark Vapes.
Dark Vapes owner Rakibul Howlader said he was the only person in his Springs Rd store at the time the infected customer visited, on both occasions, so was currently isolating.
"I was serving the customer so I have to go into isolation ... It is a bit of a shock but it has been five days already and I'm fine and I haven't got any symptoms or anything."
He had only learnt that his East Tamaki store was a location of interest this afternoon, but would be organising a thorough clean, he said.
Locations of interest
• Kmart Botany
500 Ti Rakau Drive, Northpark, Auckland, February 19 from 3.30pm-10.30pm
Casual Plus contacts, please stay home, get a test on February 24 and call Healthline on 08003585453
• Dark Vapes
East Tamaki 30 Springs Rd, East Tamaki, Auckland, February 19 from 2.30pm- 4pm
Casual Plus contacts, please stay home, get a test on February 24 and call Healthline on 08003585453
• Kmart Botany
500 Ti Rakau Drive, Northpark, Auckland, February 20 from 3.30pm-10.30pm
Casual Plus contacts, please stay home, get a test on February 25 and call Healthline on 08003585453
• Dark Vapes
East Tamaki 30 Springs Rd, East Tamaki, Auckland, February 20 from 7pm-8.30pm
Casual Plus contacts, please stay home, get a test on February 25 and call Healthline on 08003585453
