This case did this.
"We're looking at all the options," she said, when asked if people need to self-isolate from longer.
"That's something that is under active review."
She said it would be a very "sensible precaution".
McElnay said the ministry has looked at extending the quarantine period.
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.
When asked if there was crossover with other recent positive cases from the Pullman, she said she would need to check. The recent Northland positive case left the facility on January 15.
McElnay said the ministry was still investigating how it spread.
"We haven't ruled out any possibilities ...
"We are scratching our heads a little," she said, in response to a question about the most recent Pullman outbreak.
She said there are strong systems in place at the moment but said "I don't know if that's luck".
She talked up New Zealand's systems, saying they have been tried and tested.
The Hamilton individual's latest test came back positive yesterday afternoon.
They were a recent returnee from overseas.
She didn't know if the Covid-19 strain was the South African variant. 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. McElnay said the Ministry has been looking at common areas.
McElnay said there are 60 people left at the Pullman. The guests due to leave tomorrow are the final tranche to leave.
There is an "in depth review" of all MIQ facilities under way, but she could not provide a timeline on when the results would be made available.
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.
McElnay said it is critical that the swabbing is done to the "highest standard".
She said she has confidence in the testing regime.
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.
