The Health Minister is meeting with the HSE Director General to discuss ways to address the crisis in hospital emergency departments.
Latest figures show 578 people were on trolleys at hospitals around the country this morning.
The total is down from the past two days, in which record numbers of more than 600 were recorded.
60 people were on trolleys at University Hospital Limerick today, according to figures released by the Irish Nurses and Midwives Organisation (INMO), with more than 30 on trolleys at five other hospitals.
Speaking to Midlands Radio, Minister Harris said he expects the HSE to redouble its efforts and to do more than outlined in the winter initiative.
"I really am sorry for Irish patients and indeed for their staff working in our hospitals... the experience and conditions that they're having to put up with at the moment," Minister Harris insisted. "It isn't acceptable."
The HSE has warned that the flu outbreak, which is adding to numbers on trolleys, has yet to peak.
Assistant National Director for Health Protection Kevin Kelleher says it could take two months before it abates.
"We anticipate that we've still got another one to three weeks of upwards, then it will start coming down," he observed. "So you don't really see the lessening of the impact for around six-eight weeks."
Meanwhile, the INMO has called for 'cross-border cooperation' to relieve the overcrowding situation in Letterkenny University Hospital.
The organisation says the hospital has seen an increase of 10% in emergency department attendances.
Maura Hickey, INMO Industrial Relations Officer, said: “This is such a crisis the INMO is also calling on HSE management to immediately engage with neighbouring health services, including in Northern Ireland, to see what additional capacity it can supply in the interests of patient care.”
Earlier, Transport Minister Shane Ross said he spoke to Minister Harris this morning, and that he expects his Cabinet colleague to 'kick ass' when he meets the head of the HSE today.
Minister Ross told Pat Kenny: "It's unreasonable to expect him, as Minister, to micromanage the service [...] but there obviously is a big problem there."
