Prime Minister Jacinda Ardern says there are four new cases of Covid-19, one of which is an Auckland hospital worker.

The total number of cases is five.

Ardern also revealed the Devonport Covid-19 case is the Delta variant.

The PM says there usually is another tranche of test results received later in the morning.

Jacinda Ardern doesn't yet have full information about close contacts and she says an update will be provided at 1pm. But she says the co-worker of the 58 year old man - who was the original case announced - was one of the people who tested positive. The other three new cases are contacts of that person.

"At this stage it's telling us it's behaving like Delta...previous variants...you didn't necessarily have everyone you have close contact with [testing positive]."

The four new positive cases "means level 4 is the right decision", the PM says. People need to take this seriously, she says.

With one of the new cases a health worker at Auckland Hospital, staff and patients on wards where they worked are being tested, the prime minister says. The person was fully vaccinated.

Jacinda Ardern told Morning Report the new cases are the workmate of the current case and their close contacts. The information was received very late last night, she says.

The government will reveal new rules for mandatory mask use today.

Masks are currently compulsory on public transport, flights, taxis and in closed spaces where physical distancing is not possible.

Yesterday, Prime Minister Jacinda Ardern said Cabinet recently decided to mandate mask use in certain other situations.

Public health professor Michael Baker says like measles Covid-19 is a true airborne virus that spreads best through human aerosols.

Baker says New Zealand hasn't really embraced masks very well, but if people do go out during the lockdown, they should wear one.

More locations of interest are expected to be announced today. The Ministry of Health website will be updating the locations during the day - here's the list so far.

Crumb Grey Lynn - Thursday August 12 from 10am to 10.10am

Star and Garter Hotel Coromandel - Friday August 13 from 6.39pm to 7.40pm

Umu Cafe Coromandel - August 13 from 7.40pm to 8.30pm

BP Gas Station Coromandel - Saturday August 14 from 9.30am to 9.40am

Driving Creek Railway Tours Coromandel - August 14 from 10.30am to 10.50am

Jacks Cafe & Bar Coromandel - August 14 from 10.50am to 11.30am

Hereford 'n' a Pickle Coromandel - August 14 from 1.25pm to 2.15pm

Taras Beads Coromandel - August 14 from 3pm to 3.10pm

Richardsons Real Estate Coromandel - August 14 from 3.30pm to 3.35pm

Umu Cafe Coromandel - August 14 from 6.17pm to 7.11pm

Star and Garter Hotel Coromandel - August 14 from 7.11pm to 9pm

Umu Cafe Coromandel - Sunday August 15 from 10.14am to 11.10am

Taras Beads Coromandel - August 15 from 10am to 10.05am

Woodturners Cafe Thames - August 15 from 12.40pm to 1.25pm

Devonport Pharmacy Devonport - Monday August 16 from 2.15pm to 2.30pm

RNZ

Republished by Arrangement