But her own wedding plans are on hold.
The 41-year-old prime minister was planning to tie the knot next weekend.
“I just join many other New Zealanders who have had an experience like that as a result of the pandemic and to anyone who’s caught up in that scenario, I am so sorry,” she said.
New Zealand had been among the few remaining countries to have avoided any outbreaks of the omicron variant, but Ardern acknowledged last week that an outbreak was inevitable given the high transmissibility of the variant.
The country has managed to contain the spread of the delta variant, with an average of about 20 new cases each day. It has seen an increasing number of people arriving into the country and going into mandatory quarantine who are infected with omicron.
That has put strain on the quarantine system and prompted the government to limit access for returning citizens while it decides what to do about reopening its borders, angering many people who want to return to New Zealand.
About 93 percent of New Zealanders aged 12 and over are fully vaccinated, and 52 percent have had a booster shot. The country has just begun vaccinating children aged between 5 and 11.
The family from the Nelson-Marlborough region attended a wedding and other events while in Auckland earlier this month, with estimates suggesting they came into contact with “well over 100 people at these events,” Ardern said.
“That means that Omicron is now circulating in Auckland and possibly the Nelson-Marlborough region if not elsewhere,” she added.
Ardern plans to marry her longtime partner, Clarke Gayford. They have a 2-year-old daughter, Neve.
Ardern in 2018 became just the second elected world leader in modern history to give birth while holding office.