The state of the coronavirus pandemic in Ireland is "very urgent and high-risk", the director of the HSE has said.
Paul Reid said transmission levels of the virus were at a worrying level, adding that the worst fears from before Christmas had been realised.
The warning at an HSE briefing came ahead of a meeting of the Cabinet to discuss potential further restrictions.
The R value, the average number of people someone with coronavirus infects, has been estimated at 1.8.
"There is no doubt that most of our worst concerns that I outlined just before Christmas have been realised," Mr Reid said.
"There is an unprecedented and toxic combination of potential scenarios (which) have literally been realised and have emerged.
"That's a combination of a massively high level and rapidly growing daily cases, combined with (test) positivity levels that have not been seen in a long time, demonstrating a very dangerous level of transmission of the virus along with extreme levels of numbers of close contacts that people have had.
"Multiple factors have come together which we did fear would happen."
Mr Reid made a "serious and urgent" call to the public to take immediate actions, withdraw from plans to meet with family and protect themselves by remaining at home.
Meanwhile, the HSE's lead for testing and tracing revealed a 41% rise in demand for Covid-19 testing, with 63,000 referrals in the past week.
Niamh O'Beirne said they expected to see that number double next week.