There are now 120 open outbreaks of Covid in hospitals, with 442 hospital acquired cases reported last week alone, the Health Committee has heard.
The number of people on both inpatient, day cases and outpatient lists has ballooned to an "unacceptable number" a senior HSE manager said.
The Heath Committee has also heard there are now 6,000 hospital staff out of work, either because they have Covid, are close contacts or are cocooning.
Questioned the impact of Covid on other services, Angela Fitzgerald, deputy national director, Acute Operations, said the decision to curtail non-urgent elective care in March was "appropriate" but it has had "a significant impact" on waiting lists.
At the end of last year, there were 66,000 patients on the inpatient and day case waiting lists and this rose to 85,000 at the peak in the middle of the summer.
Ms Fitzgerald said this figure has come back down to 72,000 people but she said this is "obviously an unacceptable number".
She said there had been a "very challenging number" of people on the outpatient list even before the pandemic but this has now increased by about 45,000.
"They are people who need to be seen and I think they do pose a very significant challenge.
"At the macro level, the figures have deteriorated. Over the year, we've seen them going from from 66,000 to 72,000 and from 565,000 to 610,000."
Deputy Chief Medical Officer Dr Ronan Glynn said he was "disappointed" but "not surprised" by the continuing high levels of new cases.
Dr Glynn said Nphet had previously recommended mandatory quarantining of all those coming onto Ireland.
Social Democrats co-leader Róisín Shortall asked if the current system around international travel was sufficiently robust.
These are the three things that need to be done about COVID-19 in Ireland. Mandatory quarantine of international arrivals is a vital part. And the same goes for England Scotland and Wales. 4/4 pic.twitter.com/3rwEsmixiX— Dr Gabriel Scally (@GabrielScally) January 21, 2021
Dr Glynn responded, saying: "It will not stop all non-essential travel into Ireland, no."
Solidarity-PBP TD Gino Kenny said the Government's policy of living with Covid is in tatters.
"It's like living with an abuser" he told the committee.