It is not clear if an effective vaccine against Covid-19 will be found, the Republic's Health Service Executive has said.
Speaking at the body's weekly briefing today, chief clinical officer Dr Colm Henry played down hopes of an effective vaccine being available this year.
He said: "We're in an environment where there is no evidence and we are relying on the principals of infection control.
"This is a very transmissible virus. We have nothing to draw on other than what other countries are trying to do.
"Bear in mind that when HIV first came out a huge amount of investment was put into developing a vaccine which did not materialise, but a treatment did.
"There is no guarantee an effective vaccine which fulfils all the criteria of conferring immunity, being safe and being manufactured at a mass scale for a population ... there is no guarantee that will happen."
HSE chief executive Paul Reid said that as of this morning the number of Covid-19 patients in intensive care is 48, with an additional 12 suspected cases.
He said the figure is down 70% from the peak in the number of ICU cases on April 9.
Mr Reid said there are now just 800 available vacant beds out of 2,000 as demand from non-Covid cases has increased.
Some 330,000 tests for the virus have been carried out to date, with 2% of the tests positive, he said.
There have been 446 queries since May 14 from GPs regarding missing or slow test results. He said 80% of the queries have been resolved within 24 hours.
Mr Reid also said that oversight of the private nursing home sector is something that needs to be looked at.
He said: "My own reflections are there are obvious gaps in clarity regarding the responsibility and overall governance of private nursing homes in particular.
"I think any reflection at this point in time can say it is something to be looked at and is a consideration for policymakers and the HSE.
"Residents in these locations are often frail and vulnerable, and I will continuously ensure the HSE are wide open to any learnings that emerge over the next while as we are still very much living with this virus."
Mr Reid acknowledged the target of having 90% of tests for Covid-19 turned around in three days has not been met and it is currently at 83%.
"We are obviously dealing with much more complex cases now, they can take longer or mental health areas or homeless facilities. They are more complex facilities so tests will take longer," he said.
He said a new HSE dashboard is set to be published tonight showing more detailed statistics.
The coronavirus death toll in Ireland rose to 1,631 on Wednesday after a further 17 deaths were reported by the National Public Health Emergency Team.
There were 73 new cases of Covid-19 confirmed, taking the total since the outbreak began to 24,803.
