New Zealand has two new cases of Covid-19.

The couple are in their 20s and arrived from India on a repatriation flight from Delhi on June 5.

They also have an infant, who has not been tested. Director General of Health Dr Ashley Bloomfield says it is still to be determined if the child is a probable case.

The couple did not show any symptoms of Covid-19 and were picked up in health and welfare checks that are conducted every day, Dr Bloomfield said.

They were tested on Thursday in Auckland.

An interview with the couple today "may uncover a little bit more about where this couple are at in terms of the cycle of infection," Bloomfield said.

"It may well be that they had the infection and it had passed before they left India, and that these are late positive results ... we have seen this before in cases in New Zealand."

The couple have been transported from the Grand Millennium Hotel - where they have been staying - to the Jet Park hotel in Auckland.

Everyone who is at the Grand Millennium Hotel will now be tested, Bloomfield said. Everyone from the flight the couple were on have been tested.

The flight number was AI1306 - an Air India flight.

It was one of several flights MFAT organised during the past few months.

Yesterday, 7707 tests for Covid-19 were undertaken nationally.

Bloomfield is speaking at a press conference in Wellington.

Bloomfield said New Zealand is in the fortunate situation of having had so few cases, that those that are discovered receive "a lot of attention".

He said the reason we are seeing more cases this week - after several weeks of no cases - is because "we are seeing an increasing number of Kiwis returning from around the globe".

"Just to reiterate the point that I have made, there is still a global pandemic raging, and just last night the Director General of the World Health Organisation noted that the global pandemic is accelerating," Bloomfield said.

"There is an increased likelihood we will see Kiwis coming back especially from countries were there is a higher rate of infection, like India," Bloomfield said.

"This explains why we are now detecting these cases at the border.

"I do want to reiterate there is not now, nor has their ever been, stigma around Covid-19.

"It is a virus that does not discriminate and we have seen world leaders and senior public health and medical people around the globe be infected with this virus.

"Please remember it could be your relative, mother, brother or sister or father. Or it could be a friend who has returned home and is sitting in a hotel room with a positive result for the virus.

"Please be compassionate and kind. We are all in this together."

Before this week, New Zealand had 35 cases of Covid-19 identified among people returning into managed isolation.

Prior to this week, anyone who was symptomatic for Covid-19 when they arrived - or who developed symptoms - were managed in New Zealand's dedicated quarantine facilities.

Today's two cases were asymptomatic, and this demonstrated the managed isolation system was "working as demonstrated", Bloomfield said.

Today's update follows a spike on Thursday of 6273 tests, including many people currently or previously in managed isolation and who may have been contacts of recent cases.

After a run of 24 days with no new cases, two sisters were confirmed on Tuesday as confirmed cases after recently arriving from Britain.

A man who flew from Pakistan was confirmed as the third new case on Thursday and is in quarantine.

The sisters had been released from managed isolation in Auckland without a test on a compassionate exemption immediately after their mother died, and drove to Wellington where they tested positive.

They had 401 contacts - including airline passengers - of which 174 had returned a negative result by yesterday, but with most test results still pending.

Bloomfield has been under pressure in the past week after the case of the sisters revealed that the testing regime in place from June 9 had not been working properly.

Those who arrive at the border with symptoms are taken to a quarantine facility and tested.

Other arrivals are also isolated for 14 days and from June 9 were supposed to have been tested at about day 3 and day 12.

Bloomfield said yesterday that between June 9 and June 16, 55 people in managed isolation had been granted compassionate exemptions to leave early.

He has not yet been able to say how many of those left without being tested.

Bloomfield today said the Ministry of Health had made sure everyone who had left a managed isolation facility since June 9 had been tested for Covid-19 either before they left or since.