The Covid-19 message is getting very confusing. On the one hand there are dire warnings about the rising R number. Yet at the same time it will be a case of "bon voyage" to holidaymakers from Ireland flying to a "green list" European country from next week.
One thing is certain, the fluctuating R number will rule our lives for a long time to come and will even determine if we go back into lockdown.
What is R?
R is a measure of the average number of people one person with Covid-19 will infect. If R is above 1, an outbreak can grow exponentially, but if it is below 1 then the outbreak contracts.
Every infectious disease is given a reproduction number. The R number for winter flu is around 1.5. The aim is to keep it below 1 for Covid-19 - and the Republic has managed to do that for many weeks until recently.
What is the R number here now?
It has been put at 1.4 but it could be as high as 1.8. It has previously been driven down to around 0.5.
If it is lower than 1, an outbreak of Covid-19 will wear out. It meant there was room for manoeuvre when lockdown was eased and the reopening of businesses and lifting of restrictive measures were brought forward ahead of schedule earlier this summer.
That has now ground to a shuddering halt - hence the delay in opening remaining pubs. It has even meant a backward step: limiting the number of people from other households who gather in a private home.
How is it calculated?
It is calculated via mathematical modelling. If there is a low number of new cases of the virus, it becomes more difficult to get an accurate reading. For instance, if there are only 10 cases and one of them infects three others, it would push up the R rate and skew the average.
Indicators like new infections, hospital admissions and how fast the spread is in the community influences the reading. It can also be a bit behind because of the time lag between infection and people getting unwell.
On its own it is just one piece of information about the Covid-19 picture that public health doctors have to monitor.
They also look at the numbers of patients with the virus in hospital and in intensive care and GP consultations, as well as now many close contacts people who are infected have.
What is pushing up the R number?
The number of new daily cases of the virus diagnosed has crept up again and at a pace, although overall they are still relatively low.
In the darkest days around mid-April there were around 550 cases of the virus daily. This gradually fell, but now they are back to around 23 a day. The greater interaction of people with others outside their immediate family was always going to have an impact on the spread.
The challenge now is to ensure that it does not worsen and that there can be a rowing back of the increase - which may be difficult, even with the pause.