One of his daughters is a teacher and attended school on Monday.
Another daughter is a nurse at Auckland Hospital.
One them had also attended a church on the North Shore on Sunday morning with her fiance, who had not yet tested positive but was self-isolating and experiencing symptoms.
They had both also attended a nightclub in Auckland's central city on Sunday night.
The daughters live together in a flat on Auckland's North Shore, and tested positive on Tuesday night, along with their two other flatmates.
A partner of one of the girls not living in the flat is awaiting his Covid test results, but is believed to be experiencing symptoms.
One flatmate was an employee of the 58-year-old Devonport tradesman identified as Case A.
This morning genomic sequencing identified the original case as the highly-infectious Delta variant. So far there has been no link identified to a case at the border.
The father said his daughters and their flatmates sought tests on Tuesday afternoon after learning about their connection to the original case. None of them had experienced any major symptoms.
"They got tested straight after learning about the latest case in the media," he told the Herald.
"They said they had a tiny cough and slightly irritable throat, but nothing really at all what we've been told to expect. No fever or anything like that at all.
"They are feeling fine now, not under the weather at all, it was really like a bolt out of the blue."
The family also had concerns for their daughter's grandmother, who is 80. They had visited her on Monday at her home in Titirangi, and she had subsequently gone to a bowling club and shopping at a local supermarket.
She was now isolating at home and waiting for health officials to come and give her a Covid test. She had received one dose of the Pfizer vaccine.
The father and his wife had been in contact with their daughters on Sunday, and had been to their respective workplaces since.
He had received one dose of the Pfizer vaccine while his wife had not received any.
His nurse daughter was fully vaccinated, while the teacher was not.
The nurse had been to work at Auckland City Hospital on Monday. She works with elderly patients, and was well away from where any patients with Covid-19 could have been.
He said neither he nor his wife were experiencing any symptoms.
They contacted the Ministry of Health last night after learning their daughters had tested positive.
They were being treated as "close plus contacts" and had been asked to self-isolate at home for 14 days and have three tests over that period.
They were expecting contact from Ministry of Health officials this morning about an at-home test, but this had not yet occurred.
The man said he did not know where the original case originated.
He did know that the flatmate who worked with the Devonport tradesman, his father had recently returned from Australia.
"We have no idea really. It is scary. Looking at the news this morning it sounds like there could be an explosion of people, especially given the travels on the Coromandel."
He said it was "heartening" to see the lockdown measures introduced from midnight, and hoped the public would adhere to them.
"I think we have all got a bit complacent. Now it seems it can be just even the most minute of symptoms.
"It seems we could be on the cusp of a major outbreak, but as long we don't follow the path of Australia, that people adhere to the lockdown, we should be on the right track.
"It was heartening to see the Government move so quickly on this, it gives us hope."
An Auckland City Hospital spokeswoman told the Herald essential and urgent medical care continued at the hospital, and they were doing everything possible to keep the public and staff safe.
