The HSE has confirmed approximately three quarters of the health service's IT systems have been unlocked following a cyberattack last month.
The majority of the systems are now back online and available for use once again.
The HSE's chief executive Paul Reid is due to appear before the Oireachtas health committee later today detailing the "human costs" of the attack.
Officials are also expected to tell the committee that it will take months before all systems are fully restored.
The HSE's chief operations officer Anne O'Connor said outpatient appointments are still severely affected.
"Some appointments have returned. Critically, we know that in the east, in the larger hospitals, they were not as impacted as in other parts of the country.
"Sites have gradually been returning, we are at about 50-60 per cent of our capacity now. Radiology outpatients is where we had our biggest problem, so we are still significantly behind in our radiology appointments," Ms O'Connor said.
We're down to 39 #COVID19 inpatients in hospital, 13 in ICU. 22 hospitals have either 1 or no case. Hospitals are under significant challenge however due to increased Emergency Department attendances & ongoing impacts of the cyber attack. We appreciate your support. @HSELive
— Paul Reid (@paulreiddublin) June 22, 2021
While hospital services have been significantly delayed due to the impact of the cyberattack, the falling number of inpatients with Covid-19 has been welcomed by officials.
On Tuesday, Mr Reid confirmed there were just 39 people in hospital with the virus, the lowest number since September 1st, and only 13 of these patients were being treated in intensive care.
Mr Reid added that 22 hospitals in the country have one or no case of Covid-19.
"Hospitals are under significant challenge however due to increased Emergency Department attendances and ongoing impact of the cyberattack," Mr Reid said.
