Three Irish hospitals were hit during last Friday's extensive global cyber attack.
Mr Corbridge said that in a small number of cases in the a year ago, health service machines had been infected with a ransomware virus but the HSE had not paid a ransom.
Mr Cobridge said that "all [HSE] clinical services and computer systems have been protected from the virus and no data or information was compromised as a result of the attempted cyber attack".
"In all three cases, the hospital was returned to the health network and continued to deliver patient care with no impact", it said.
Microsoft patches have been added to more than 28,000 new machines and more than half of the affected Microsoft XP machines have been checked and it is expected that the rest will be visited in the next 48 hours.
The only confirmed case in Ireland so far targeted by this virus is a HSE funded healthcare unit in County Wexford - which wasn't connected to its main network.
Earlier: Workers across the Republic of Ireland and the North have been placed on high alert over cyber security.
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The PSNI said some people's systems may already be infecting and waiting to activate after the weekend. The issues were not related to the ransomware cyber attack, and affected two administrative computers that did not hold patient records.
The NHS in the United Kingdom was affected by the hack with 48 out of 248 NHS trusts affected by the hack, although this number has been reduced since the start of the attack.
Northern Ireland computer networks may have been infected by a virus that plunged parts of the NHS elsewhere in the United Kingdom into chaos, police have said.
The HSE's external IT networks will also remain offline today as a precaution. "This incident has tested our people and our processes and provided us with huge learning to build upon", he said.
"We ask anyone who has reported a child protection concern by email since Friday, or who has a concern about a child, to contact their local social work duty team immediately".
However, HSE Chief Information Officer Richard Corbridge said the 20 machines were quickly isolated from networks before it spread, with the machines replaced and the systems put back online.
Emails into the HSE will continue to be blocked until Wednesday.