Professor Philip Nolan has played down a rise in Covid cases, saying it may be part of an “exit wave”.
The former head of National Public Health Emergency Team (Nphet) modelling told reporters in Washington there were no plans to bring the group together to discuss the spike.
Earlier Taoiseach Micheal Martin said the Government is “concerned” about the increase in cases of Covid-19, but said there were no new measures currently being considered by the Government.
“We are concerned with the increase in Covid cases,” Mr Martin told reporters in Washington DC. But he said that the “advice so far is that the impact in terms of illness is not severe”. He urged people to get the booster dose of the Covid vaccine.
Mr Martin said that about 50 per cent of cases were being admitted to hospital for other reasons, but were testing positive for Covid subsequently.
However, Mr Martin said that ICU numbers were not rising at the moment. “We’ve been in consultation with the Chief Medical Officer and the Minister for Health on this and we’ll keep it under watching review.”
He said people should wear masks “where appropriate”, citing retail and public transport as well as “large indoor gatherings”. He said that people should “enjoy St Patricks Day” but they should “take basic precautions”.
In a briefing on Wednesday the Health Service Executive (HSE) said more than 4,000 healthcare workers are off work due to Covid as hospitals experience unprecedented demand from emergency patients.
The numbers attending hospital emergency departments (EDs) have been at near-record levels for the past three weeks, the HSE said .
Attendances at EDs last week were the second highest on record, just behind the figures for the previous week, and over 28,000 both weeks, officials told a media briefing.
The increase is driven by increased attendance by older people, up one-quarter on the same week in 2020 and 2021. Only half of over-75s are being dealt with in EDs within the target time of nine hours.
Hospitals in Galway and Kilkenny, along with St Vincents and the Mater in Dublin, are under the heaviest pressure, officials said, but smaller hospitals such as Bantry and South Tipperary are also very busy.
HSE chief executive Paul Reid urged people to “get back to basics” around public health measures over the St Patrick’s Day holiday, and pointed out that mask-wearing is still recommended “in the appropriate settings”.
He likened the coming bank holidays to a “double weekend” in terms of pressure on the health service, but officials said they were supportive of the Government decision to make this Friday a bank holiday in recognition of the efforts of workers during the pandemic.
Covid-19 patient numbers in hospital have risen 32 per cent in a week and 72 per cent in the last two weeks, according to the HSE.
Mr Reid said the 1,082 patients with Covid-19 in hospital on Wednesday - the highest figure in over a year - were impacting heavily on the hospital system.
However, the level of sickness doctors are seeing is not as high as before and of those in hospital with the virus, 48 per cent came in with other illnesses and were later diagnosed with Covid-19, he pointed out.
He urged people to get vaccinated or boosted if they haven’t already done so, to stay at home if they have symptoms and to wear a mask where advised.
The high circulation of Covid-19 has also been felt in nursing homes, where 300 have outbreaks and 96 new outbreaks were notified in the last week.
The proportion of over-65s among those in hospital has risen to 73 per cent, from 51 per cent previously.
Un- or under-vaccinated people are still disproportionately represented in hospital, where 35 per cent of patients with Covid-19 have not completed a vaccination course, and in ICU, where the figure is 37 per cent.
Of the estimated 566 patients who are currently in hospital because of Covid-19, only 44 per cent have received a booster.
The BA.2 subvariant of Omicron accounts for 90 per cent of cases at present, up from 70 per cent in late February, HSE chief clinical officer Dr Colm Henry said.
There was evidence of re-infection among people who previously had the Delta variant and, to a lesser extent, Omicron/BA.1 cases, he said.
Officials said 4,102 healthcare staff are currently off work due to Covid-19 and 540 are off work in nursing homes.
Asked whether people should wear a mask over the St Patrick’s Day festivities in light of the increase levels of infection, Dr Henry advised that people should exercise their own judgement but that “the wiser thing might be to wear one” in congested settings.
As for what will happen over the coming while, Dr Henry said there was a “great deal of uncertainty”.
The Mater hospital in Dublin appealed to the public on Wednesday to aboid its emergency department due to the “extreme pressure” on services.
The hospital says the pressure is the result of large numbers contracting Covid-19, high presentations at the emergency department and high levels of staff absence due to the virus.
Non-urgent patients who are attending the emergency department are experiencing lengthy waiting times.
Public health officials have expressed concern over the rise in case numbers and hospitalisation, but have so far held back from calling for a re-introduction of mask mandates or other restrictions.
Meanwhile, a total of 183 outbreaks were notified last week, up 55 on the previous week, according to the Health Protection Surveillance Centre.
The biggest increase was in residential institutions, with 55 outbreaks last week compared to 34 the week before. Most of these - 35 - were in centres for disabilities.
There were 30 outbreaks in hospitals, up two, and 45 in nursing homes, up eight. The biggest hospital outbreak involved 13 case and the biggest in a nursing home, 24.
All 15 school outbreaks notified last week occurred in special education.
There were 10 outbreaks in the Traveller community, and three among prisoners and prison staff, one of which involved 23 cases.
The HPSC said 24 Covid-19 were notified to it last week, with an average age of 82 years.
Cases are now rising across Europe and, in some, hospital numbers are also increasing.
In China, case numbers have reached a two-year high and millions of people have been locked down as the country struggles to contain Omicron variant outbreaks.