Taranaki DHB says the six people in Stratford who tested positive for Covid-19 were reluctant to get tested and have not been using the contact tracing app.
The group got swabbed yesterday, more than a week after the virus started showing up in the town's wastewater.
Taranaki DHB medical officer of health Dr Jonathan Jarman told Morning Report it had taken "disease detective work" to find them, and the severity of their illness was behind the decision to get tested.
"I think in the end, they realised that this was potentially a serious illness. Certainly, one of the family members, one of the people involved with this cluster said that it was the sickest they had ever been, and I think then the penny dropped, and they agreed to testing."
One member of the group is now in hospital.
Dr Jarman said the three adults and three children have kept to themselves in Stratford, but there may be one or two locations of interest.
He said the fact the group did not use the Covid Tracer app means authorities are having to use "old fashioned" contact tracing.
Despite all of that he's feeling relieved.
"My main feeling actually is relief. We've finally managed to track them down and now we know what we're dealing with. I think the other thing is that Covid is coming to Taranaki. It's here now in Stratford, there are likely to be more cases. So really, it's a really strong message that if people are not already vaccinated, they should be seriously thinking about it now."
Dr Jarman said the three children have not been to school or pre-school during their infectious period.
