Nelson-Tasman Omicron cases attended Auckland wedding before positive tests

The Nelson-Tasman Omicron cases attended a wedding in Auckland prior to their positive results.

The Prime Minister said initial estimates suggested there were more than 100 people at the wedding and other events the cases attended.

The entire country is moving to the Red traffic light setting from 11.59pm on Sunday, Prime Minister Jacinda Ardern announced in a media conference.

The cases - all part of the same household - flew to Auckland on January 13 to attend a wedding "and other events" on the weekend of January 15 and 16, Ardern said.

"An initial estimate suggests that there were well over 100 people at these events," she said.

A fully-vaccinated flight attendant on the same flight as the Nelson-Marlborough cases tested positive for Covid-19 on Saturday. They worked four flights while infectious.

Another attendee at the wedding tested positive for Covid-19 late on Saturday.

"We don't yet have a clear lead on the index case that links this family to the border as we have with our other Omicron cases to date," she said.

"That means Omicron is now circulating in Auckland and possibly the Nelson-Marlborough region, if not elsewhere."

Director-General of Health Dr Ashley Bloomfield said the Auckland and Nelson-Tasman locations visited by the family had been identified.

The locations would be added the Ministry of Health's list of locations of interest once confirmed.