There is one new case of Covid-19 in managed isolation - but none in the community as health officials continue to wrestle with containing the Valentine's Day cluster.

The focus remains on KFC Botany - a family member of one of the Papatoetoe High School students who tested positive had been told to stay home and isolate, but instead went to work at the fast food restaurant on Monday.

The Ministry of Health said today there were three categories of contacts related to KFC. Eleven people in the first category are close contacts plus who also worked there and are in 14 day isolation.

Members of the public who entered the store at the time are close contacts who must get tested today, and casual plus contacts who went the drive-thru should also get tested today. Both groups should isolate until receiving a negative result.

As the potential exposure was on Tuesday, day 5 is today. People are advised to get a test tomorrow and remain in isolation until they have a confirmed negative result.

Ardern said the isolation measures went further than the usual practice.

The Covid-19-infected KFC worker is part of the now 12-strong Valentine's Day cluster.

They are a household contact of Case I, the Papatoetoe High School student who tested positive for the virus earlier this week, Case J, who had been at work at Kmart in Botany, and Case K, an infant sibling.

Case I was the first to test positive on Tuesday – the day after today's case went to work at KFC.

But advice from officials has been for all household contacts of all Papatoetoe High School students to remain at home until they had received a negative Covid-19 result – hence Ardern's frustration today.