The 'R' rate of the coronavirus is now estimated to be 1.8 in Ireland, with the latest data said to be showing causes for concern.

At a Department of Health briefing this evening, Chair of the NPHET Epidemiological Modelling Advisory Group, Professor Philip Nolan, said "there are a number of causes for concern" in the latest data.

"We've seen a very sharp increase in the number of cases being reported over the last week," Prof Nolan said.

"The average number of cases being confirmed per day has more than doubled in that week."

The 'R' rate has increased from around 1.3 last week and is "significantly higher than what we have been reporting recently and is very close to 2".

Prof Nolan said there is a real risk that community transmission could develop over the coming weeks.

"This emphasises the need for each of us to be extraordinarily cautious, so that we don't contribute to any further transmission of the virus."

The reproduction rate is the number of people who become infected from each positive case and efforts seek to keep the 'R' rate under 1.

The Acting Chief Medical Officer, Dr Ronan Glynn said that everyone in Kildare, Laois and Offaly needs to pay particular attention if they have any coronavirus symptoms, and double down on health measures.

There was a large number of cases notified to the National Public Health Emergency Team in these counties, he said, which will be part of new case numbers tomorrow.

Over the past 14 days, he said, 226 cases have arisen in the counties, representing 48% or almost half of all cases during that time period.

Dr Glynn said that while the majority of these cases could be accounted for by outbreaks, the volume of cases was significant and the main priority was to ensure that they did not lead to widespread community transmission in the region.

He advised people in Kildare, Laois and Offaly to be vigilant to symptoms of Covid-19 and to adhere to the advice on hand-washing and mask wearing.

Dr Glynn said "we need to keep community transmission low, in order to ensure that schools reopen to the fullest extent".

He also said cases need to be kept low to allow health services to continue and non-Covid services to resume.

"At the moment, thankfully we don't have significant levels of transmission. We have significant clusters."

Dr Glynn said "we fully expected to get large clusters like this, it's an entirely normal part of dealing with a pandemic. It won't be the last time we have to deal with something like this."

The Department of Health was today notified of five additional deaths and 69 new Covid-19 cases.

Four of the deaths are late notifications, relating to April and June.

The number of Covid-19-related deaths in Ireland is now at 1,768, while the number of confirmed cases has risen to 26,372.

Of the new cases notified today, 37 are men and 31 are women, while 65% are under 45 years of age.

Thirty-nine of the cases are confirmed to be associated with outbreaks or are close contacts of a confirmed coronavirus case. Two of the cases have been identified as community transmission.

Twenty-two of the cases are located in Offaly, 19 in Kildare, eight in Laois, six in Dublin and 14 are spread across eight other counties.

Asked if localised lockdowns should be considered in Kildare, Laois and Offaly, the Acting Chief Medical Officer said "you can't rule anything out".

Dr Glynn said the situation will be monitored very closely and further guidance will be given tomorrow.

He told the briefing that there are four factories in the midlands which are seeing a spike in Covid-19 cases. However, he said that the workers live around the counties so urged caution in the area.

Those over the age of 70 in Kildare, Laois and Offaly should take particular care, Dr Glynn said, and they should limit the number of people they are in contact with to a very small extent.

He also said that 11 people with Covid-19 are in hospitals, five of whom are in intensive care units.

Prof Nolan urged restraint when it comes to house parties, saying that outbreaks of the virus could lead to vulnerable people being severely impacted by Covid-19.

"A house party is the perfect way to spread this out more widely into the community and hence, into people who are vulnerable," he said.

Asked about whether it will be recommended by NPHET that secondary school students wear face coverings in classrooms, Dr Glynn also said the Health Protection Surveillance Centre is currently looking at the issue of face coverings for teenagers.

He said he expects there will be guidance on the matter in the coming days.

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The Government earlier warned that Ireland is in a very "delicate position" in terms of Covid-19.

Assistant Secretary General at the Department of An Taoiseach Liz Canavan told a briefing at Government Buildings that in the last week there have been more cases - every day - and there are rising numbers of cases in vulnerable groups.

She said that the more the country opens up, the more opportunity there is for the disease to spread. 

Ms Canavan said there were outbreaks in a number of workplace settings, more young people are getting the disease and there has been a shift in the location of the majority of cases from Dublin to other counties. 

Separately, GPs have reported a large increase in the number of patients contacting them with symptoms of coronavirus since the bank holiday weekend.

In Northern Ireland, it has been announced that the reopening of pubs has been "paused" until 1 September.

Speaking this afternoon, First Minister Arlene Foster said the 'R' number there is now between 0.8 and 1.8, adding that the chief scientific advisor "probably thinks it is about 1.3".

From Monday, face coverings will be mandatory in enclosed spaces in Northern Ireland where social distancing is not possible.