The Covid-19 burden on acute hospital care has increased considerably, according to the Chief Medical Officer, Dr Tony Holohan.
In a letter to Minister for Health Stephen Donnelly, he warned: "If the recent rising trend in hospitalised cases continues, we are likely to see increased pressure on the hospital system over the coming weeks.
"This will further reduce hospital capacity to admit patients for scheduled and unscheduled care."
Mr Donnelly, who was sent the letter on 10 June, confirmed to RTÉ News yesterday that rising infections were putting pressure on the health system.
He also said further Covid-19 restrictions are not under consideration.
The number of people in hospital with Covid-19 has increased from 355 - when Dr Holohan expressed his concern at rising cases - to 515 this morning.
However, the outgoing CMO confirmed in his letter that "over half were hospitalised for Covid-19 disease (51%) with the remainder categorised as asymptomatic infectious cases".
Dr Holohan said a "number of epidemiological indicators have deteriorated in recent days" and this suggested that levels of coronavirus transmission have increased.
He added: "The increasing prevalence of the BA.4 and/or BA.5 Omicron sub-lineages in Ireland (which appear to have a growth advantage over the BA.2 sub-lineage) is likely contributing significantly to the current epidemiological profile."
The CMO said current public health advice continued to be that "anyone diagnosed with Covid-19 should self-isolate for seven days from date of onset of symptoms, or if asymptomatic, date of first positive test".
Mask wearing is advised on public transport and in healthcare settings, he said.
"Vulnerable individuals are advised to consider wearing masks in crowded indoor settings, [such as] social gatherings or other activities and events," Dr Holohan added.
He also urged people to book a Covid-19 booster vaccine if they were eligible for one.
Earlier this week it was announced that Professor Breda Smyth has been appointed as the interim Chief Medical Officer, replacing Dr Holohan, who steps down from the role at the end of the month.
