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Petrie's daughter, who is studying at the University of San Diego on a rowing scholarship, tested positive not long after learning her roommate had contracted the virus.
"Building resilience," Petrie wrote on Instagram
"Less than 2 weeks in the US & Addie has Covid. Now in iso.
"No symptoms, otherwise loving Uni & rowing."
The mum of three told the Herald, despite testing positive, her daughter is in good spirits.
"As a mother and as a parent it's hard to know because they are so far away because I can't get to her right now but she's amazed me with her strength and positive attitude."
After receiving the news about her roommate's positive result, Addison got herself tested, which came back positive.
She was then was moved to a "Covid apartment" which she will call home for the next five days.
"The good news is she is surrounded by lots of the rowing community and they are rallying around her," Petrie said.
"We certainly didn't expect her to get it within two weeks of arrival that was a bit of a shock."
Sharing a hug on social media, Petrie said, "As a mother it is so hard to let go! But she is off to live her life, and I couldn't be more excited and proud. Look out, San Diego!"
The beloved broadcaster said she is grateful her daughter isn't too sick as she has no family with her in San Diego.
"It's great she doesn't feel too sick because if she was feeling sick it would be super stressful," she said.
"Not only are we raising awareness and supporting Breast Cancer Cure, but we are showcasing our talented fashion designers.
"It was fun to do the shoot with my daughter Addison, who's turning 18 and embarking on her path as a young woman. Every woman, young and old, needs to be reminded to look after themselves."
With the past two years being so disruptive, Petrie is glad her daughter can finally live her young adult years.
"She has had a hard two years of homeschooling and cancelled regattas and lockdowns so for me it shows you can still live your life especially at that young age."
Despite getting Covid nearly 10 days after arriving in San Diego, Petrie said her daughter is thriving.
"Her resilience is amazing it just makes me so proud that she can get through this.
"It's a big challenge moving countries going all by herself to a university, to then get settled in and get that [Covid] I'm just so proud of her."
Last year the mum-of-three, who was a cheerleader in the late 80s and early 90s, regularly delighted viewers by breaking out her fancy footwork on air and in November her teenage daughter Liv even uploaded a video to social media of Wendy, her husband Ross Peebles and their family dancing up a storm in their Auckland home.
For now, Petrie is looking forward to a more normal school year, "where I'm not homeschooling my intermediate-aged son Zach, and our swimming daughter Liv can get back in a pool again and go to competitions."
And she hopes to be able to travel overseas once more.
"I'm really looking forward to travelling again. I really hope we can travel and have the overseas 50th birthday trip I had really wanted."