COVID-19: What we know about New Zealand's 17 cases of community transmission

Since Prime Minister Jacinda Ardern and Director-General of Health Dr Ashley Bloomfield announced New Zealand's four new cases of community transmission on Tuesday, the outbreak has evolved into a cluster.

The family's movements, through work, school and a trip to Rotorua and Taupo have now brought New Zealand's cases of community transmission to 17.

Three colleagues at Americold cold storage facility in Mt Wellington have been diagnosed with COVID-19 - and passed it on to seven family members. 

A relative who is a student at Mt Albert Grammar has the virus. 

They came to school on Monday when they were not showing symptoms and attended five classes - making 100 close contacts.

A Finance Now workmate of one of the four original cases contracted COVID-19 and was admitted to North Shore hospital but has since been discharged. 

Since then one of their family members has also contracted the virus.

Now the race is on to prevent those cluster branches spreading further and Dr Bloomfield says Kiwis should expect the numbers to rise.

"What we know about clusters, as we've found out in the past is that they do continue to grow so we fully expect there will be further cases."

Some students at Mt Albert Grammar have been sent letters saying they must self-isolate for 14 days. Other families in the area have been told to stay vigilant for any COVID-19 symptoms.

Dr Bloomfield announced on Thursday that treatment of positive cases will now be more strict - requiring them to go into a specialist quarantine facility. 

"This is different to how positive cases were managed when we were last at levels 4 and indeed 3," he said.

"[It] shows how serious we are about limiting any risk of ongoing transmission."

However, the news wasn't well-received by those who have tested positive for COVID-19.

"I think there was some reservation initially but having spoken to the public health unit again today, everyone's quite comfortable about this," Dr Bloomfield said.

Auckland is currently on day two of three in alert level 3 lockdown and the rest of the country at alert level 2.

The Prime Minister will make a decision about whether to extend the lockdown at 5:30pm on Friday. 

There are now 17 cases linked to the cluster, and New Zealand has seen them get out of hand before.

The Bluff wedding got up to 98 and Marist College got up to 96. 

But already there's one additional 'probable' case within the community linked to the same cluster so containment of this cluster is highly unlikely to have been achieved yet.