NPHET has raised concern that Ireland is in the early phase of an increase in Covid incidence driven by the Delta variant.
There have been 448 new cases of Covid-19 reported in Ireland, as the death toll from the virus has reached 5,000.
This comes following two more deaths related to the virus reported today.
The number of cases may change due to future data validation.
Speaking at a briefing on Thursday afternoon, Deputy Chief Medical Officer Dr Ronan Glynn said: "Yesterday, the weekly update on deaths was given as 4,998.
"We are reporting an additional two deaths today, to bring the total number of deaths to date to 5,000."
As of 8am today, 44 Covid-19 patients are hospitalised, of which 14 are in intensive care units.
There have been 12 additional hospitalisations in the past 24 hours.
As of Tuesday, 29 June there have been 4,109,474 doses of Covid-19 vaccine administered in Ireland.
2,443,921 people have received their first dose and 1,665,553 people have received their second dose.
Chair of the NPHET Irish Epidemiological Modelling Advisory Group Professor Philip Nolan said in a statement: "We have seen an increase in incidence over the last ten days, raising the concern that we are in the early phase of an increase driven by the Delta variant.
"Incidence is growing at 2% per day, reproduction number is now above 1; estimated at 1.0 to 1.2.
"Delta is much more transmissible, and it is vital we continue the basic measures to prevent transmission while the vaccination programme rapidly gives us all protection from the virus."
Director of the National Virus Reference Laboratory Dr Cillian De Gascun added: "The prevalence of Delta in the community is increasing, but its effect on hospitalisations and severe illness is still emerging.
"We do know it is the most transmissible strain of Covid-19 to date. Emerging evidence from the UK shows Delta roughly doubled the risk of hospitalisation.
"As proven throughout the pandemic, monitoring evidence and timely action protects us all."
