Today's case is a man in his 40s who arrived in the country on Sunday, July 12 from Africa.
Regional Public Health are interviewing him further about his travel history.
The man was staying at the Sebel Manukau and tested negative on around day three of his stay. He then tested positive on around day 12 and was being transferred to a quarantine facility in Auckland, the Ministry of Health said.
"This case reinforces why we test people twice during their time in managed isolation," the ministry said in a statement.
"A second test around day 12 is needed because the infection may take longer to develop in some people. It's an important check used to find out if a person is safe to leave managed isolation."
It has now been 84 days since the last case of community transmission.
There are two new recovered cases today, taking our total number of active cases to 21.
There is no one in New Zealand receiving hospital-level care for Covid-19.
The total number of confirmed cases is now 1206 - the number we report to the World Health Organisation.
Yesterday 2830 tests were completed, up again on the past two days.
The total number of tests so far is 451,616.
Covid app
The Covid Tracer app has now recorded 618,800 registered users.
There have been 80,669 posters created to date and 1,545,145 poster scans.
The ministry said it was continuing to remind New Zealanders to keep a record of where they've been as this remains one of the best tools in the continued fight against Covid-19.
"That's why we are continuing to encourage all New Zealanders to download, register and use the app."
No cases yesterday
There were no new Covid-19 cases in New Zealand yesterday.
Director general of health Ashley Bloomfield yesterday said five cases had recovered, so there were now 22 active cases. None of the patients required hospital-level care.
There were 2419 tests conducted on Wednesday, just under 2000 of them in the community.
Bloomfield said this showed that the message of getting tested seemed to have boosted testing numbers.
He would meet DHB bosses today to ensure there was good testing access for the community seven days a week, and to clarify that tests are funded.
Meetings with clinical leaders were also being held to drive home the need to increase testing rates, he said.
Medical Colleges survey
There had been 500 responses as of yesterday to the GP survey sent out earlier this week, which would look at, among other things, how often Kiwis declined to be tested.
"Even though we have no community transmission, if you have been offered a swab there is a good reason for that. Please take that test," Bloomfield said.
The case definition changes at the end of June separated people who were of high suspicion - such as border workers - and those needing to isolate while waiting for test results compared to others not considered higher risk and didn't need to isolate after tests.
Bloomfield said there would be a rolling programme to test people working at quarantine and managed isolation facilities.
Mobile data
Health Minister Chris Hipkins said the cost of mobile data was a barrier to people accessing Covid-19 information.
The ministry was working with Spark, Vodafone and 2degrees to make information websites free for mobile access. Data will be charged back to the ministry.
He said he had met with the assurance committee for contact-tracing and he expected, within a day or two, to receive its final report and recommendations.
He would outline the details of the report next week, he said.