Director of public health Caroline McElnay has confirmed a community Covid-19 case in Hamilton.

The person had been isolating since January 30 and had returned three negative tests, the most recent on February 2.

She said the ministry was advising people to cancel events. A Hamilton Waitangi Day event was cancelled this morning, with the hosts referring to information obtained from a "credible health source" there was a new positive case of Covid-19 in the community.

"We are acting out of an abundance of caution," she said.

McElnay this afternoon said there is a requirement that everyone who comes out of the Pullman has to self-isolate for five days after they left.

This case did this.

The person was at the Pullman from January 16-30. The person was on the same floor as some of the other recent positive cases.

The individual's latest test came back positive yesterday afternoon.

They were a recent returnee from overseas.

Further tests are under way and the person is now at Jet Park.

The person lives with two other people, who are being treated as close contacts. Both of them have returned negative results.

All people wore masks at communal places in the house.

McElnay said there are no locations of interest at this stage.

She said the only people who need to get tested are people who are symptomatic, as per normal.

The Waikato DHB has expanded the number of testing stations.

On the Pullman, she said an investigation into the facility continues.

The last guests there are due to leave tomorrow.

McElnay is "very confident" that this person did not go out while they were isolating.

"They have stayed at home, they haven't been anywhere else," McElnay said.

She has a "high degree of assurance" that this case is contained.

McElnay was not sure of the chain of transmission and said this person "could be a historic case" but they are running more tests.

The person is still asymptomatic.

There are two other Covid-19 cases today - one at the border and one historic.

The Ministry of Health this morning played down the seriousness of the situation, saying the risk to public health is low.

"People in and around Hamilton should not be alarmed," the ministry said in a statement this morning.

The new case is someone who stayed at the Pullman Hotel and they have been self-isolating since they returned home on January 30.

Officials said the person returned three negative tests before they tested positive for Covid-19.

"The case reinforces the importance of the self-isolation and repeat testing strategy we have adopted around people leaving managed isolation at the Pullman."

The Ministry of Health statement came after a Hamilton Waitangi Day event was cancelled as, according to the hosts, a "credible health source" said there was a new positive case of Covid-19 in the community.

At first, health officials would not confirm the case but Hamilton Mayor Paula Southgate told Stuff the Ministry of Health was investigating a "potential low-risk case".

"It's understandable that people are anxious. Everyone wants to keep this virus at bay," she said.

"It certainly isn't time to panic or anything," she said, adding that she hadn't been given a reason to be concerned at this stage.

Today's new case is the fifth case of someone testing positive for Covid after they had left managed isolation at the Pullman Hotel.

Covid-19 Response Minister Chris Hipkins ordered an investigation into the hotel to figure out why the virus had spread.

He has not made the results of that investigation public.

Hipkins also ordered a "deep clean" of the hotel before anyone new was allowed to isolate at the facility.