In a statement, Minister Harris said the health service is experiencing extra pressure because of the flu season.
In the right and centre, Billy Kelleher TD commented on the 656 people waiting for a bed in hospitals yesterday, the highest number since records began.
"I am committed to breaking the cycle of overcrowding in the health service".
Mr Varadkar on Thursday apologised to patients who had experienced long delays and waits on trolleys in emergency departments over recent days.
The figures come as the INMO's annual figures show that nearly 100,000 people were waiting on a trolley or on a ward past year.
The Health minister also spoke with the CEOs of the country's hospital groups, stating that what we're seeing in hospitals this week is unacceptable.
The overall figure for the country is 677 - which is a new record.
The second highest rate of overcrowding this week was at St Luke's Hospital, Kilkenny, with 191 patients on trolleys, followed by Cork university Hospital with 136 patients.
The INMO recently released its annual figures for 2017, which revealed that nearly 99,000 patients were left waiting on trolleys past year, with the highest figure recorded in University Hospital Limerick (8,869).
TAOISEACH Leo Varadkar and Health Minister Simon Harris both apologised today after nearly 600 hospital patients became the latest victims of the overcrowding crisis.
Ms Fogarty has also said that more robust action from management is called for to tackle the constant overcrowding problem in the emergency department at UHL.
She said: "If you think your child has the flu next Monday, please don't bring them to school because then we will have a significant outbreak".
He said: "I am anxious about the spread of the flu when kids go back to school".
MUH Clinical Director Dr Kieran O'Connor said: "In this context, visiting is being restricted to the hospital in the interest of patient safety".
He said that people with flu-like symptoms should visit or phone their Global Positioning System rather than go to the hospital's Emergency Department.
Doctors say they are seeing a mix of the H3N2 strain - the so-called "Aussie flu" - and influenza B.
Nearly 200 people have been hospitalised with the flu and a small number - less than 10- of people have died.
He said: "I want to reassure the public that all the winter plan measures funded by increased investment by Government, like increased access to home care, transitional care and diagnostics along with additional acute bed capacity, are being implemented".