Middlemore Hospital has resumed elective surgeries this week after suspending hundreds of operations to care for victims of the Whakaari/White Island tragedy.
Forty-seven people were on the small, volcanic island when it erupted on December 9, leaving dozens seriously injured.
Patients flooded into hospitals and urgent calls were made to skin banks across the globe, as New Zealand suddenly needed 120sq m of donated skin for grafts.
Counties Manukau District Health Board chief medical officer Dr Peter Watson said the same volume of work they would usually see in a year arrived in just over a day.
"It was an extraordinary demand."
They had worked closely with other hospitals and stopped elective surgeries which have resumed this week, he said.
In the 10 days that followed the disaster Middlemore Hospital postponed 220 elective surgeries.
Around 600 surgeries are expected to be postponed by the end of January.
Following the disaster lots of staff members gave up their holidays or returned early from leave to work very long days, Watson said.
They were joined by a burns surgeon from Australia who cancelled a booked vacation to help, and a Canadian specialist.
It was the first time that a national 'multiple complex burn action plan' was activated, he said.
"We had a lot of commitment, energy and generosity from people but there are also lots of learnings, from which I mean, you don't know how big the challenges are until you are actually in them."
Watson said 13 patients remained in four hospitals across the country – including the two injured New Zealand tour guides and others from America, UK, China and Germany.
Eight of those patients are being treated at Middlemore Hospital.
Thirteen other patients were transferred to Australian hospitals, eight of which remain in the care of two New South Wales public hospitals and three of which continue to receive specialist burns care at The Alfred.
At least two among that Australian group remain in a critical condition.
After the dead skin was removed patients had required multiple temporary skin grafts which could hold for a few days or about a week - "it's not long," he said.
"That's why people have to go back to theatre quite a lot."
Both the dressing changes and grafting were performed in theatre.
Most of the patients had progressed to the stage where they could have their own skin now grafted onto their burns, he said.
"This is a long-term healing process, and for many of them it will take years."
Watson said there were two important things to remember about skin.
"One it prevents infection, and second it keeps you warm. When you have lost lots of skin you are prone to temperature control problems and infection."
Patient rooms and the theatre had to be kept in the low 30 degrees, he said.
While it was "not quite like working in a sauna" the room was noticeably warm and for medical staff donning theatre gowns it could make for "hot, sweaty work".
It could be physically hard work as well as psychologically as people were witnessing trauma, he said.
Director-General of Health Dr Ashley Bloomfield said the tragedy placed sustained pressure on the health system.
But at short notice six Australian nurses and one Kiwi had volunteered to support their colleagues at Whakatane Hospital to ensure specialist care over the holiday period.
"District Health Boards, particularly in the greater Auckland area, have also been working closely together to ensure other patients can get acute and urgent surgeries."
The Ministry also wanted to acknowledge international assistance received, particularly from Australia, but also the UK, Canada and the United States.
Aussie nurse felt connection to NZ
Clinical Nurse Consultant Madelaine 'Maddie' Hooper volunteered without hesitation when staff at her workplace, The Royal Brisbane Hospital, were asked to help.
"I remember seeing the reports of the White Island eruption on the news," Hooper said.
"I was quite upset to hear about it and so when they asked if anyone would be interested in going to help out I put my hand up straight away."
Hooper had previously worked at Christchurch Hospital and her godmother's family is from the Whakatāne area.
She said she already felt a connection to New Zealand.
Hooper found out she had been selected on Christmas Eve and arrived in Whakatāne on the 30th.
She said the group of nurses had been warmly welcomed by everyone at the hospital and by the community.
Back home, Hooper, who has a masters in traumatology, works in a critical care outreach position.
Hooper will return to Australia on January 13 and said she has also made plenty of friends whilst in New Zealand.
"It's certainly brought a group of six Australian nurses close together."