This week's cyber attack at Waikato District Health Board has been described as the biggest in New Zealand history.
It's expected to be at least another week before the DHB can rectify its hospital's IT system, Waikato DHB chief executive Kevin Snee told Newstalk ZB host Heather Du Plessis-Allan.
Meanwhile, two Air New Zealand flights have been cancelled as a result of the hacking. The airline was unable to get a negative Covid-19 result certificate for a crew member scheduled to work on the flights.
Snee said his understanding was a manual certificate was not accepted by the airline.
There were lots of experts working with the DHB but it had proven more complicated than anticipated, he said.
"It's probably the biggest cyber attack in New Zealand's history. We are dealing in uncharted territory here," Snee said.
"The most significant issue in the short term is radiotherapy, because it is dependent on the computer technology."
Arrangements had been made with other hospitals to perform radiotherapy, Snee said.
Of 111 elective surgeries planned at Waikato Hospital on Thursday, 88 were able to go ahead as scheduled.
Unfortunately, it had been necessary to cancel a number of specialty outpatient clinics. A list of those was available on the DHB website, a statement published on the DHB's website said.
Anyone needing acute surgeries would get treated, Snee said.
The DHB had to cancel appointments at a number of clinics including, cardiology, maxillofacial, dental and dermatology.
The chief executive said he couldn't say how many staff hadn't been paid properly.
"We have got prezzie cards that people can use if they are in difficult circumstances, if they haven't got anything in the bank and they need something to tide them over but I'm not sure if any of them have been used but they are certainly available.
"We have worked around the clock to rectify that but the circumstances are difficult," Snee said.
Snee promised next week's pay roll would be better managed better.
AUT professor of Computer Science Dave Parry said the attack was the worst in our country's history.
"Shutting down hospitals for more than a week is a huge attack and clearly there is a massive amount of effort going into repair this."
Meanwhile, doctors at Waikato Hospital are reverting to whiteboards and hardcopy records to continue treating patients.
One doctor working at Waikato Hospital's emergency department yesterday said they were rolling up their sleeves and dealing with the crisis - like it is 1999.
All hospital's under the DHB - including Waikato, Thames, Tokoroa, Te Kuiti and Taumarunui - had been affected "to varying degrees".
The DHB has been encouraging the public to keep Waikato Hospital's Emergency Department for emergencies only.
If you need immediate or urgent help, please continue to call 111. If it is not an emergency, please phone Healthline on 0800 611 116, visit your GP or local urgent care centre.
For those trying to contact their loved ones in hospital, please consider using personal mobiles where possible, the DHB said in a statement earlier this week.