The head of the Health Service Executive has said the damage caused by the recent cyber attack had a “devastating impact”.

Chief executive Paul Reid said it wiped out more than 2,000 systems and “completely disarmed” many clinical and medical teams of the basic tools they need for treating patients.

“We continue to make further progress, but it can’t be overstated the devastating impact that this has had on our health service,” he said.

“It’s practically been a complete wipeout of over 2,000 systems, all having to be rebuilt from a base level and re-established in a very controlled manner and in a co-ordinated safe manner.

“Many organisations, public or private, could be completely overwhelmed by any such impact.

“But for the relentless passion, commitment of our healthcare teams, the relentless focus to protect our patients, it’s unmatched in any organisation I’ve ever seen.”

The ransomware attack resulted in the HSE having to close down all of its IT services, causing widespread delays and the cancellation of appointments at hospitals across the country.

Mr Reid said it has left a trail of destruction, which the HSE has to clean up.

He added: “It’s not just about getting a decryption key and starting back to where you were – in essence, we have to really rebuild our systems in a whole new way.

“There’s been quite a serious impact and trail of destruction left behind as part of the cyber attack, which we have to clean up.

“In acute hospitals we’ve continuously made progress on patient administration systems, radiology diagnostics, laboratories, medical oncology, endoscopies, and we are starting to make some progress in further services in the hospital.

“There is no single hospital now has fully integrated services and full connectivity between hospitals.

“Some have connectivity within their unit, within the hospital and bubble, but increasingly more hospitals are getting access to more services, but not in a fully integrated manner.”

He said staff have had to manually record everything in the last three weeks, before inputting it into the system, which is highly technical and leaves “no margin for error”.

“But there’s no doubt that every action that they take, every minute of every day, carries enormous risk in the current environment without the full basic tools they need,” he added.

Mr Reid said the HSE is working with gardai, digital publishers, search engines, social media networks, and its legal team to monitor ebsites used by criminal organisations and search for any patient data that may have been stolen.

The HSE also said that less than 25% of devices have been decrypted.

HSE chief operations officer Anne O’Connor said there are still significant delays across all its services.

“We know that people are concerned in terms either if they attend an emergency department what their experience will be, but also just the delays in their care if they had appointments cancelled,” she added.

“There are risks associated with our own staff, who are flat out. This is day 21 for us and we have people who have been working relentlessly trying to either address the IT element or the services.

“There are higher risks of clinical errors in manual transcription and the access of systems.

“The longer that goes on and the more tired staff are, we have to keep an eye on that.

“There are risks of potentially delayed diagnosis and other risks arising from cancellations and the slowing of services.”