"There is a critical window over the next eight weeks where any significant increase in close contact is likely to lead to a significant fourth wave of infection in the range of that experienced in January 2021."
The Health Protection Surveillance Centre (HPSC) has reported that six more people with Covid-19 have died in Ireland.
The HPSC has also been notified of an additional 411 confirmed cases of Covid-19 in the country, bringing the total number of confirmed cases in Ireland to 235,854.
There has been a total of 4,687 Covid-19 related deaths in Ireland.
In a statement issued on Wednesday, Chair of the NPHET Irish Epidemiological Modelling Advisory Group Professor Philip Nolan said the reproduction number of the virus is high, being currently estimated at between 1.0 and 1.3.
He explained: "If the epidemic is growing again now, the doubling time is estimated at 35 days or longer.
"When comparing the risks of levels of social mixing now and over the coming months with that which applied in 2020, we need to take into account the B117 variant and how easily that transmits, and we must also take into account the vaccination-induced immunity that will progressively protect us and make it more difficult for the virus to transmit.
"Vaccination will contribute greatly to the easing of measures in the coming months, however now we need to keep transmission as low as possible so that vaccination of the population can take place and have the desired effect."
Acting Chief Medical Officer Dr Ronan Glynn added: "There is a critical window over the next eight weeks where any significant increase in close contact is likely to lead to a significant fourth wave of infection in the range of that experienced in January 2021.
"We can and should be optimistic for an enjoyable summer ahead but, in the meantime, we have to continue to work together to prevent a further wave of infection as we accelerate vaccination across society and maintain our health services."
Of the deaths announced on Wednesday, the median age was 79 years and the age range was 49 to 87 years.
Of the cases notified today, 202 are men and 209 are women.
70% are under 45 years of age, with the median age being 35 years old.
150 of the cases are in Dublin, 31 are in Donegal, 25 are in Kildare, 25 are in Wexford, 21 are in Offaly and the remaining 159 cases are spread across 17 other counties.
Over the past 14 days, 7,669 cases have been notified, with the national 14-day incidence rate for Ireland now standing at 161 cases per 100,000 population. The five-day moving average is 509 cases per day.
There were 297 patients with Covid-19 in hospital at 8am on Wednesday morning, with 67 patients in critical care. There have been 16 additional hospitalisations in the past 24 hours.
As of last Sunday, 28 March, there have been 806,541 doses of Covid-19 vaccine administered in Ireland.
580,857 people have received their first dose and 225,684 people have received their second dose.
