The Health Service Executive's Chief Clinical Officer has said it is too early to say if patient information has been accessed and taken away in Friday's ransomware attack on the HSE computer systems.
Speaking on RTÉ’s This Week programme, Dr Colm Henry also said the HSE cannot predict yet when IT systems will be fully restored.
He said he anticipates the disruption will "go well into this coming week".
Dr Henry explained that part of the assessment into the attack by IT experts and with external support is to assess if patient records have been encrypted.
He said their priority is focused on the patient information system where their records, lab results and all of that information is stored on the servers.
Dr Henry said the vaccination programme is "unaffected" and the testing system is also fully capable and continuing.
"Fortunately those parts of pandemic response are ploughing ahead and uninterrupted," he said.
The HSE said in a statement earlier today, that over the last 24 hours it has been focusing on identifying clean back-up data and establishing a foundation on which it can begin to restore servers.
It says the priority is on patient management systems, which will enable access to patient records and diagnostics.
The integrated system has been disconnected, allowing certain databases to operate in isolation.
The HSE said "thankfully not all hospitals are on the central system and have not been impacted to the same extent".
Patients across the country, whose important medical appointments have been cancelled tomorrow or later next week, are waiting to hear when they will be rescheduled.
People with radiotherapy, X-ray and MRI appointments are among those affected. Chemotherapy and dialysis services are both continuing.
Hospital emergency departments remain open and appointments for vaccination against coronavirus are going ahead.
The HSE says that anyone who has an appointment for a Covid-19 test should attend as planned but there could be delays with test results.
Work is continuing this weekend to assess the nature and extent of the cyber attack.
It is not known yet what level of data might have been encrypted by the hackers. The HSE said it would be some days before the system was fixed.
A Consultant in Emergency Medicine at Connolly Hospital Blanchardstown in Dublin has said she is worried about the impact on emergency departments following the cyber attack.
Speaking on RTÉ's Brendan O'Connor programme, Dr Emily O'Conor said the hospital is busy and things are moving slower since the HSE's IT systems were shut down as a precautionary measure.
She said the impact varies around the country.
"There is no single information system that is used in every emergency department but we have all been affected.
"From the moment a patient arrives and needs to register we have resorted to predetermined registration numbers that we can use for patients."
Dr O’Conor said triage and patient history now have to be manually taken as she outlined the main challenges hospitals are facing without access to electronic systems and records.
"The tracking of patients around the department, even a medium sized department like mine in Connolly, there can be 80 patients in there at the one time and you can track electronically what stage of care that patient is in and that is what has now reverted onto white boards.
"And the biggest problem for all of us is our laboratories is our diagnostics and X-ray systems."
She said all the systems are down and having to copy images onto discs and transfer manually onto other hospitals.
Dr O'Conor said there are variations to how the impacts are being felt as some hospitals will hold charts electronically and others will have paper systems.
She said there are concerns that a lot of treatment that should be happening routinely next week will not be, as a result of thie disruption.