The Deputy Chief Medical Officer has said there is "a critical window" in the coming weeks to prevent a "significant" fourth wave of Covid-19 infection and people "have to work together" to avoid such a situation.
Dr Ronan Glynn was speaking as the National Public Health Emergency Team reported six further virus-related deaths and 411 new cases.
There are a total of 297 patients with the disease in hospital, 67 of whom are in intensive care. There were 16 additional hospitalisations in the past 24 hours.
Dr Ronan Glynn said: "Together with all of the basic public health measures with which we are all now so familiar, vaccination will significantly reduce risk of Covid-19 over the next relatively short period of time.
"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.
"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."
He appealed to people who are meeting up to do so outdoors, to keep their distance and to wear masks.
The chair of NPHET's Irish Epidemiological Modelling Advisory Group said the epidemiological situation is stable but precarious and it has not changed much in the last ten days.
Professor Philip Nolan said that Ireland is "in a very static situation".
He said that, on average, 533 new cases were reported over the past seven days and the figure has been between 500 and 600 for the entirety of March.
Prof Nolan said the situation "doesn't seem to be getting worse but unfortunately it doesn't seem to be getting better".
Speaking at a NPHET briefing this afternoon, he said this is "translating into a significant number of people per day becoming so unwell that they require hospital care".
"We are in a very static situation"
— RTÉ News (@rtenews) March 31, 2021
.@President_MU says there has been an average of between 500-600 cases per day for the entirety of March, adding that the overall picture is one of stability | Live updates: https://t.co/nnmabA21mx pic.twitter.com/Zdyn4rAw4E
NPHET said that all of the six deaths reported today occurred in March.
The median age of those who died was 79 and the age range was 49-87 years.
There has been a total of 4,687 Covid-19 related deaths in Ireland.
Of the 411 new cases confirmed today, 202 are men and 209 are women, 70% are under 45 and the median age is 35.
Dublin accounts for 150 of the cases, there are 31 in Donegal, 25 in Kildare, 25 in Wexford, 21 in Offaly and the remaining 159 cases are spread across 17 other counties.
The total number of cases stands at 235,854.
As of last Sunday, 28 March, 806,541 vaccine doses had been administered in Ireland with 580,857 people receiving their first dose and 225,684 people receiving their second dose.
Prof Nolan said that "fortunately" the number of people in hospital continues to decline.
He said the intensive care figure is declining "very slowly" with "an unfortunate regular admission of between of 20-25 people per day for the entire month of March".
He welcomed the fact that the number of deaths reported per day is back into single figures, saying this is an indication that those in long-term residential care and other older citizens are protected through vaccination and the link between case numbers and fatality is beginning to be broken.
"That effort to keep close contacts low is preventing a worsening of the situation"
— RTÉ News (@rtenews) March 31, 2021
.@President_MU says the average number of close contacts has remained constant this month, adding that the majority of people have worked hard to keep that number low | https://t.co/nnmabA21mx pic.twitter.com/BwQQRIwczy
Prof Nolan said the increase in cases in those age 18 and under over the last few weeks appears to have stabilised over the last week.
He said there had been some change in population behaviour at the beginning of March, but the majority of people have "worked hard" to keep their social contacts low and this effort is preventing any further worsening of the situation.
The reproduction number of the virus is the same as last week at between 1 and 1.3, Prof Nolan added, but he has "a sense of population effort to prevent the situation disimproving".
He urged people not to the increase their contacts over the coming weeks as "the risks are enormous".
Prof Nolan said that if the B117 variant of the virus did not exist and "we were doing all the things we were doing right now" the reproduction number would probably be 0.8.
"Please do not increase your social contact over the coming weeks"
— RTÉ News (@rtenews) March 31, 2021
.@President_MU says increased social contact in the coming weeks would result in "real difficulty", adding that the reproductive number of the virus is drifting toward 1.3 | Live updates: https://t.co/nnmabA21mx pic.twitter.com/24HYTVvaxQ
Dr Glynn told the briefing that he is aware of those who are visiting households who are not vaccinated and are not wearing masks.
He urged them to meet up outdoors, to keep their distance and to wear face coverings.
Dr Glynn said: "We can't afford to have intergenerational, inter-household mixing and especially not inside.
"Now, more than ever, it would be such a shame over the coming days for families or households that meet up or older, or vulnerable people in those households were to get infected with this virus, when these are the very same people who will be offered a vaccine over the next four to six weeks."
Discussing a possible fourth wave, @President_MU says a marginal rise in reproduction number from 5 April could see cases rise to 1,000 per day into late June, while a medium-level rise in social contact would result in a "very significant" surge | More: https://t.co/nnmabA21mx pic.twitter.com/BuT28rCkBm
— RTÉ News (@rtenews) March 31, 2021
Prof Nolan outlined a number of modelling scenarios in relation to the virus.
He said that from 5 April, if the reproduction number increased from the current situation (between 1.1 to 1.3) to 1.3, cases would increase slowly to about a 1,000 a day into late June and early July.
If there was a slow or medium increase in close social contact from 5 April, Prof Nolan said, it is highly likely
that it would precipitate a very significant fourth wave of disease.
He said that even a very marginal increase in the reproduction number to 1.5 would between 5 April and the end of September would result in the region of 200,000 additional cases.
He said a medium level increase in close social contact would result in a very significant surge of disease somewhere in the region of half a million cases between 5 April and the end of September.
Prof Nolan said when half the population is vaccinated, it will be twice as difficult for the virus to transmit.
He said: "The amount of protection that we're buying for each other and for our health services ... in a pandemic that we've been living with for 56 weeks, is really quite extraordinary."
