More people will miss out on elective surgery this week at Waikato Hospital as the DHB struggles with no computer system because of last week's massive ransomware cyber attack.

The DHB is likely to manage 80 per cent of the scheduled elective surgeries, and who was seen depended on how much laboratory and radiology services are required for their surgery, it says.

Last week, it carried out 299 elective surgeries and cancelled 60, and it expects similar figures this week.

The same applies to outpatient clinics and it expects 20 per cent of them will be cancelled.

Last week, 2776 outpatients appointments were seen and 602 were cancelled.

DHB chief executive Dr Kevin Snee told Morning Report it will probably be next week before the IT systems are fully operational again.

"We're a very complex system and this has proved more complex to address than was first thought," says Snee.

"We also have to careful in addressing the problem that when we stand up the system, it doesn't run into problems again."

Carrying out hospital procedures is more difficult than usual.

"We can't send, for example, lab tests electronically to the wards, it has to be done by paper and printing out ... everything is much slower than usual.

"Staff are getting into a routine now about how they manage things."

Snee says there has not been any further communication from whoever carried out the ransomware attack.

"I think our ability to respond to this as a country and an organisation is being tested - we're coping well so far and we're getting good help from our national and regional colleagues. I'm confident we'll continue to provide good service and I'm incredibly impressed by what work staff are doing."

Executive director of hospital and community services Chris Lowry says while they know the number of clinics and patients booked, they are having to manually track down names and vital clinical information.

Staff are having to search for the original referral.

''This means GPs refer patients to our services to see if we can pull out their referral letter which will have clinical information on it, which will be relevant to their visit.''

Lowry says patients could check on clinics on the DHB website, but if in doubt, they should phone.

Extra staff will be needed to put the patient notes into the new IT system, Lowry says.

''There will be a whole lot of patient information which we will look to scan on to the electronic clinical record and other patient activity data, lab results etcetera that we will need to get into the system.''

It's all part of a recovery plan being worked on now, she says.

Pay errors

Snee says last week there were errors in pay which were corrected over a pay run the following day, and minor corrections were needed the day after that.

"As soon as we realised there was a problem we pulled out all the stops to sort it out.

"We had credit cards as a backup with $50 on them for people in particular hardship but none have been used.

Small errors are likely again, and staff have been given phone numbers to call and speak to a manager in case of hardship, Snee says.

"I'm very confident that pay this week will be much more representative of the true pay ... if there's any errors we will rectify them immediately."

New Zealand Nurses Organisation kaiwhakahaere Kerri Nuku says there's some anxiety and frustration about pay errors.

"But I think hearing that when there had been errors, that they had been rectified relatively quickly, gives nurses and healthcare workers some reassurance ... but it doesn't stop the fear and anxiety.

"The nurses I've spoken to are just concerned and I think once they get through this week and see that the glitches may not be something that impacts on their lives, it might be a lot easier."

-RNZ/Andrew McRae.