The Prime Minister said the bereavement subcluster associated with Mt Roskill Evangelical Fellowship Church in Auckland was a "trouble spot".
"While there is no evidence of significant spread outside of the Auckland cluster, this event does raise the possibility that more people have been exposed within what is already our biggest cluster to date."
The announcement has had an immediate effect on planned events in Hawke's Bay this weekend.
The Tarzino Trophy Daffodil Raceday – Bostock New Zealand Spring Racing Carnival this Saturday will go ahead but with restrictions and changes, said Hawke's Bay Racing Inc chief executive Darin Balcombe.
The Raceday will be limited to owners and sponsors split into "well-segregated" areas with their own entrances and toilets.
There will be up to 100 in each section but they will have to stay at tables of 10 where there will be food and bar service. There is a total limit of 500 patrons.
Balcombe said all the rooms and a couple of the marquees were all sold out and the day is the second biggest derby outside of the Livamol Classic.
They rely heavily on the Spring Carnival for the racing season and the implications will be significant, "especially from the hospitality side".
If level 2 restrictions were in place for the Livamol Classic on October 17, the implications would become "exponential".
"We've got huge bookings for Livamol day, it's more a struggle of where to find room for everyone than anything."
A full crowd gathering to watch a Magpies game will also not yet be possible this weekend.
The first Magpies home game against Counties Manukau this Sunday can be attended by sponsors, members, existing hospitality and ticket bookings and Napier City Council suite holders. There will be no more ticket sales.
Hawke's Bay Rugby commercial manager Dan Somerville had said he was confident the rugby union could successfully deliver a match under level 1 or 2.
"We are very lucky to have recently played the club rugby semifinals and finals at McLean Park under level 2 regulations so we are confident that we can safely accommodate the commitments and bookings that we have.
"Our sponsors and members are very loyal so we will be doing our best to ensure they are all looked after."
Somerville said McLean Park is an ideal venue for the regulations with ample seating, multiple gates and entry points to stands and corporate areas.
However, he had his "fingers crossed" that they would have been able to sell tickets to fans and have a crowd at the first home game.
The Hawke's Bay Secondary School Sports Awards which were set for October 19 at the Napier Municipal Theatre were also cancelled due to the uncertainty around levels and disruption to secondary school sport that Covid-19 has caused.
Hastings Boys' High School principal and chairman of the Hawke's Bay Secondary School Sports Committee Rob Sturch said secondary school sport has faced "unprecedented disruption" which meant the traditional awards format will not be possible.
Sport Hawke's Bay chief executive Mark Aspden said the organisation, with support of secondary schools across the region, has decided to recognise a wider range of achievements with no specific categories instead.
Excellence certificates will be awarded to students who have excelled in sport over the past 12 months and recipients will be profiled across media channels.