The number of cases of Covid-19 will reach 7,000 per day amid "rampant" levels of transmission, the head of the Health Service Executive (HSE) has warned.
Paul Reid said the daily number of positive coronavirus tests is expected to be more than 6,000 on Monday.
The chief executive said the HSE is currently meeting the demand for tests that is "coming at us at an absolutely phenomenal rate".
The HSE is seeing positivity rates hit 30%, with some centres recording levels of up to 50%.
The health system was notified of 4,962 confirmed cases on Sunday.
"Some of the backlog is being washed through but the minimal rate is certainly above a base of 5,000 people," Mr Reid said.
"That's what we are dealing with. This is now rampant in terms of transmission levels.
"We probably have seen a massive multiplier effect - we have seen rapidly growing cases, rapidly growing positivity at 30% yesterday, multiplied by numerous contacts that people have, and that comes together in a very congested period of time.
"In the last week, we have carried out almost 140,000 completed tests. We built the capacity up to 175,000 tests per week."
Mr Reid said they are now prioritising testing people who are symptomatic.
"We have said to those who are close contacts to do exactly what we have always said - to restrict their movements - but we are prioritising our tests for those who are symptomatic," he added.
"The GPs are being swamped equally. They are seeing coming through their referrals to us - they have seen up to 90% testing positive.
"If you are a close contact, you do exactly as we asked in the past and restrict your movements for 14 days. If you have symptoms, please contact your GP and you will be referred for a test."
Mr Reid said it is not possible to give a test to everyone who wants one because of current levels of demand.
"It's growing at a pace no-one could have projected - 30% positivity rate from our total testing," he added.
"We know there are centres across the country which have had 50% positivity rate.
"The message to people is that Test and Trace is no longer our first line of defence - our first line of defence is for the public to really work with us.
"Drastically, radically and urgently reduce contacts. Stay at home."
He said the high transmission levels are beyond anything forecast and the community transmission rate is well above what they are seeing in test centres.
Mr Reid also said that building extra Test and Trace capacity would not help reduce the level of transmission.
"The Test and Tracing system is functioning but unless and until we drastically change what is happening in terms of public transmission, how we are meeting people, how we are engaging with each other," he added.
"If get back to a manner in which we did in the first phase, we can and expect to turn this around."
There are currently 744 patients with coronavirus in hospital, which is rising at a rate of 20% per day.
There are currently 65 people in intensive care (ICU) with Covid-19.
Mr Reid said that if current projections continue, they could see hospital cases rising to between 1,500 and 2,500 with ICU numbers expected to increase to between 250 and 430 cases.
"They are levels that puts us at high and extreme risk in terms of ICU," he added.
Ireland has a total number of 285 ICU beds, which can increase up to 370.
Mr Reid said that around 3,000 healthcare staff are off because of Covid.
Turning to vaccination, Mr Reid said the HSE will deliver 40,000 of the Pfizer-BioNTech jab every week.