There is a lack of evidence to back up whether the physical distancing rule to protect against the spread of Covid-19 should be one or two metres, the chair of the advisory group behind the controversial decision said yesterday.
Dr Cillian de Gascun, head of the National Virus Reference Laboratory, said the two-metre distance was decided on because the coronavirus was "an emerging and dangerous" pathogen in March.
Picking two metres was "prudent and cautious", he added.
He was speaking as pressure grows from the hospitality trade and businesses to reduce the two-metre rule to one metre to allow for more customers.
"If you want to look for evidence based on one or two metres, you are not going to find a huge amount," Dr de Gascun said.
The gap is aimed at protecting people from being infected through droplets spread when someone coughs or sneezes.
The expert group looked at the 1.8m rule from the Centre for Disease Control in the US to protect people from flu, and also the gap introduced as part of the response to Sars.
Chief medical officer Dr Tony Holohan said sometimes the National Public Health Emergency Team (Nphet) doesn't have the evidence and works on the precautionary principle.
He was speaking after another nine people were reported to have died from coronavirus.
It followed the milestone on Monday when no daily deaths were announced.
A further 37 new cases of people diagnosed with the virus were reported, most of them women.
However, HSE chief clinical officer Dr Colm Henry said the virus is "virtually extinguished".
He revealed that just 2pc of people are now testing positive - compared with an earlier pandemic rate of 25pc.
The turnaround time for test results is now three days, and lower for those who test negative, Dr Henry added.
Questioned on the phased reopening of childcare facilities from the end of June, Dr Holohan said work is under way in drawing up guidelines with the Department of Children.
There is no zero risk but the Nphet was aiming to mitigate the risk of these services resuming.
The Health Protection Surveillance Centre, the country's disease watchdog, is also involved in providing guidelines and will set out its advice "at the right time", Dr Holohan added.
Earlier yesterday Federation of Early Childcare Providers (FECP) chairwoman Elaine Dunne said there is no guidance in place to support the reopening of childcare facilities for essential workers on June 29.
A survey conduced by the FECP shows that of 609 providers, 60pc would definitely not be opening on that date.
Questioned on when residents of nursing homes could see loved ones, Dr Holohan said the Nphet was particularly sensitive to the impact that loss of visitors was having on residents.
"We are looking to see if we can be creative and sensitive to the impact. It is a significant challenge," he said.
Commenting on the controversy around how private nursing homes handled the coronavirus threat, he said it was not a case of blaming anyone, and the objective at this stage was to learn lessons.
It was unhelpful to blame visitors to nursing homes for helping to spread the virus and they do not provide an explanation for how it got into homes, Dr Holohan added.
Meanwhile, data gathered by the Mental Health Commission has shown a notable decrease in the total number of suspected and confirmed cases of Covid-19 across the 181 mental health services it has been monitoring across the country.
It expressed concern that some mental health staff were still waiting for Covid-19 test results last week, despite the introduction of guidance over a month ago that required all staff to be tested.
Chief executive John Farrelly said: "Any significant delays in the receipt of staff test results were escalated to the HSE last week.
"The HSE responded to these escalations and informed us that there are different testing pathways for mass testing and for outbreak testing.
"We understand that, while outbreak testing is prioritised and has a very short turnaround, there may be some delays associated with mass testing.
"However, from our monitoring process last week, 32 out of 181 services reported that they were awaiting one or more staff test results.
"While the considerable majority of tests have been completed in services, it remains a concern that the guidance requiring all staff to be tested was introduced more than a month ago and it took so long to complete."
Following concerns raised by the commission in its last weekly risk-rating report that some services remain confused over which public health guidance document they should be following for the prevention and management of the virus, the HSE has since said separate advice is in development for approved centres that take acute admissions.