There are about 40 people in the Whanganui District Health Board region currently considered close contacts of a Covid-19 case.
A Ministry of Health spokesperson said the 40 Whanganui contacts were registered at its National Contact Tracing Centre.
That number was considered a "live" figure that was constantly being updated.
"We expect the numbers of identified contacts to continue to grow across the coming days," the spokesperson said.
Meanwhile, about 10 staff from the Bayleys Whanganui and Ruapehu have been self-isolating after attending a conference in Auckland where there was a positive case of Covid-19.
They are part of the wider group of 40 people in self-isolation in the Whanganui DHB area as at 8am on Friday, because they were contacts with a Covid-19 case.
All of the group from Bayleys Whanganui have returned negative day five and day 12 tests and expect to be out of self-isolation from Saturday.
"I guess it creates a little bit of anxiety because if it's the Delta variant, it's highly contagious," Bayleys Whanganui managing director John Bartley said.
"You just do your part and go and get tested."
The 10 who are in self-isolation were at the real estate company's national awards night at the Spark Arena in Auckland a fortnight ago.
At that same event - as well as a national Mitre 10 staff function a day earlier - was a bartender who since tested positive for Covid-19.
Bartley said self-isolation for he and his staff was much like life under alert level 4 - only they could not go out to the supermarket or to other essential services.
Instead they would get groceries delivered.
Bartley said he had confidence in the Ministry of Health's dealing of the matter - saying he was alerted as a close contact quickly and had received two calls "checking in" on him.
The contact tracing was being carried out by Public Health Units and coordinated by the National Contact Tracing Centre at the Ministry of Health.