New Zealand will keep seeing cases of Covid-19 until the rest of the world stamps it out.

There are 20 active cases of the virus staying in managed isolation - all of them linked to overseas travel.

Patients are being held in managed isolation, one person is receiving hospital level care.

It has led to reassurances that the country is not seeing any community transmission.

Professor David Murdoch told Kate Hawkesby we would have tracked down community spread by now.

"There's a lot of testing being done. We would see a lot more if that was the case, so I think we are relatively confident of that." 

However, he warns that there's a lot of infection worldwide, and that the borders will remain a key focus in our battle.

"Travellers coming back are the main risk, and the focus has got to be on rapidly identifying cases at the border and acting appropriately with quarantining." 

• Four new Covid-19 cases at border; one in hospital