There is still one active case of Covid-19 in New Zealand, but there have now been 15 straight days of no new cases to report.

Yesterday there were 3007 completed tests, bringing the total number of tests completed to date to 291,994.

The total number of confirmed and probable cases remains at 1504, while the death toll is unchanged at 22.

There is no one receiving hospital care for Covid-19.

Half of the 16 significant clusters have closed, which is unchanged from yesterday.

A cluster is considered to be closed when there have been no new cases for two incubation periods (ie, 28 days) from the date when all cases have completed isolation.

In its update today, the Ministry of Health welcomed the latest guidance on the use of masks from the World Health Organisation.

That guidance was consistent with the ministry's current advice that "mass-masking" is not required.

"The WHO emphasises that masks should be part of a comprehensive strategy and that much of their updated guidance relates to countries with a high degree of community transmission," the ministry said in a statement.

"Fortunately, in New Zealand we are increasingly confident we have no community transmission which supports our ongoing move down through our alert levels."

The NZ Covid Tracer app has now recorded 511,645 registrations – an increase of 10,645 since this time yesterday.

The ministry continued to urge New Zealanders to use the app because it helps with contact tracing.

New Zealand's active case remains an Auckland woman in her 50s who was reported as a suspected case on May 1, and who then tested positive on May 21.

She has been in isolation since the start of alert level 4 lockdown in March.

She has had symptoms in the previous 48 hours; a recovered case is someone who has been symptom-free for two days

The most recent new case was first reported on May 15 - a Christchurch boy aged between 1 and 4 who was linked to the Rosewood rest home.