The number of Covid-19 "clusters" has doubled since Monday with the largest new group a Royal New Zealand Air Force rugby team that visited the United States.

Overall, the number of people in New Zealand confirmed with Covid-19 in the past 24 hours increased from 552 to 600, with another 47 probable cases.

The number of clusters has also increased from seven on Monday to 14 today.

Those identified as clusters are not necessarily new or recent cases, rather they have now been linked because they have been in the same place together.


Most of these clusters have a link to someone or several people who have travelled overseas recently.

The largest remains Auckland girls' school Marist College, which has 48 confirmed and probable cases, with one new case since yesterday.

Of the newly-identified clusters the largest is linked to Blenheim, where nine cases have been tied to the RNZAF rugby team's trip to the United States.

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A Nelson Marlborough Health spokeswoman said the RNZAF cluster stemmed from one of the first confirmed cases in the region, on March 22. Three cases remained in the area, while the rest had returned to their normal areas of residence.

A New Zealand Defence Force spokesman confirmed to the Herald the RNZAF cases related to the men's and women's team attending the recent Anzus Shield rugby tournament in Denver, Colorado, in mid-March.

Teams from Australia and the United States were also present.

The competition was to run from March 12 to 21, but was cancelled after three days due to the global spread of Covid-19.


All cases had been self-isolating since returning, and no cases required hospital care, the spokesman said.

Meanwhile, eight cases have been confirmed at Christchurch compost company Living Earth, and another eight from a wedding in Bluff at Oyster Cover Restaurant and Bar on March 21.

The wedding, understood to be of about 80 guests from out of town, was held when the Government was still permitting gatherings of up to 100 people.

Bluff Community Board chairman Ray Fife said he was shocked to hear the news and had not received formal notification of the cluster.

''I just hope those people who have been confirmed [as having the virus] make a full recovery.''

Alzheimers NZ chief executive Catherine Hall confirmed one of the Marlborough cases was a client of Alzheimers Marlborough, and staff involved had been in self-isolation since they were identified.


That case was part of a cluster of six, and originated from one person returning from overseas who tested positive on March 20.

The cases linked to the boat builder came after an employee was skiing in Colorado, a Ministry of Health spokeswoman said.

There are two clusters in Hutt City, one with four and another three, while Auckland charitable care provider for people with disabilities Spectrum Care now has four cases, up from two on Monday.

There have been 11 new cases added to the Redoubt Bar cluster in Matamata, now 23 stemming from St Patrick's Day celebrations on March 17.

Focus: An urgent testing station has been setup in Matamata as cases spike in the small town. Video / Alan Gibson

The cluster from the World Hereford Conference in Queenstown has also increased, with 24 cases now, up from 19 yesterday.

There are cases recorded in all 20 district health boards (DHBs). To date nationally 14 cases are in hospital, one person has died and 74 people have recovered.


Today's new statistics also show Southern DHB now has the highest number of cases, with 98, with Auckland DHB recording 97 cases and Waitematā 86. Tairāwhiti has the lowest number, with one case recorded.

The age group most affected is 20 to 29 years, with 169 cases, and women so far are disproportionately impacted with 350 cases compared to 289 in men, with eight not specified.

There have been 21,384 lab tests since March 3, and an average of 1777 in the past week.

Of the total cases, 53 per cent are linked to international travel and 29 per cent linked to known cases.

Just one per cent has been linked to community transmission and the origins of 17 per cent of cases are still being investigated.

Otago University Professor and epidemiologist Sir David Skegg told Parliament's Epidemic Response Committee he believed the testing had been skewed to people who have been overseas, and was therefore a poor indication of community transmission.


Prime Minister Jacinda admitted in Tuesday afternoon's press conference authorities weren't testing widely enough to tell where the community outbreaks were, so the case definition has been expanded.

Travel history and connection with a case was now not essential to being tested.

"I want more tests. We've built the capacity for more tests."

She said clinicians were deciding when it was appropriate to extend test criteria, not politicians.

Clusters under investigation - including probable cases

• Marist College, Auckland: 48 cases

• World Hereford Conference, Queenstown: 24 cases


• Redoubt Bar, Matamata: 23 cases

• Group travel to US, Wellington: 16 cases

• Assisi Rest home, Hamilton: 14 cases

• Boomrock wedding, Wellington: 11 cases

• Living Earth, Christchurch: 8 cases

• Air Force rugby team US visit, Blenheim: 9 cases


• Bluff wedding, Bluff: 8 cases

• Marlborough Alzheimers, Marlborough: 6 cases

• Hutt City cluster 1: 4 cases

• Hutt City cluster 2: 3 cases

• Colorado ski-boat builder, Auckland: 4 cases

• Spectrum care, Auckland: 4 cases