Neither of the two have tested positive for Covid-19.
"They have both tested negative at their three-day test," the statement said.
"Their day-12 test is due to be undertaken over the weekend."
The official would not say exactly when the pair arrived back into New Zealand or which country they came from.
The spokeswoman said this was not the first time someone who had returned from overseas had been given an exemption from undergoing managed isolation at a hotel - instead carrying out their 14-day quarantine at home.
She acknowledged that such exemptions were given only under strict conditions or compassionate reasons - in this case, a medical reason.
It was allowed when those needing to stay in 14-day managed isolation could not have their health needs met in a hotel.
The current case was being run in accordance with health guidelines and was "not unusual".
The Herald has sought further information about the case, including which country those in the household had returned from and how many similar exemptions had been granted.
Neighbours find out from security guards
A neighbour who contacted the Herald said he only spotted the guards outside the house yesterday.
He said he asked the guards what they were doing and they said it was Covid-related.
The man said the news was alarming.
"I've got family that stay just nextdoor to them and I don't want them catching it."
On the street today, a witness said up to three security guards were stationed outside the house, some wearing masks.
Two were seen at one point sitting in their car when it started to rain.
The other was seen walking around the property.
The news comes after director-general of health Dr Ashley Bloomfield said on Facebook this morning: "What we have put in place since April 9 is that everyone coming across the border, bar a very few exemptions, has to do that 14 days of managed isolation - so not even isolating at home."