The rise in Covid-19 cases in Ireland has shaken us out of our comfort zone and revealed a series of potential weaknesses in our defences against the spread of the virus.
The downward trend in infections until recently sparked hopes it was nearly defeated.
The rise in new cases may not be large - but as long as the pandemic lasts we will be living on a knife edge.
Q The 23 cases reported on Thursday sparked concern - why is there such worry?
A They must be seen in the context of the previous two weeks when there was a turnaround after a drop in infections.
One of the drivers has been travel-related infections where somebody who arrives here as a tourist or a returning holidaymaker tested positive after picking up the virus abroad.
Q If everyone who arrived here self-quarantined for two weeks, they would surely not pass it on to others?
A On Thursday, 15 of the 23 cases were linked to travel.
Doctors were on quite a complex journey around the country to trace contacts of at least one of the infected people who came here from abroad. The self-quarantine is not mandatory so there is the potential for a repeat.
Q Is the danger that a small cluster can mushroom into a much bigger outbreak?
A In the case of a tourist who is infected, they could be in Dublin one day, Galway the next, and then on a tour of Kerry.
This poses a risk of spread that might be difficult to trap.
People can be infected and not have symptoms, unwittingly passing the deadly virus on.
Q How good are public health systems at tracing?
A There was criticism of the tracing here and this summer will provide a new challenge. The downloading of the Covid tracing app by 1.1 million people will help. Users will get an alert if they are a close contact.
Q Once a close contact is found, how often are they tested?
A There are two tests - one at the beginning and another on day seven. But there is another weakness here which could undermine the trail to bring a cluster under control.
Around 40-50pc are not taking up the offer of a test on day seven so they could be spreading infection.
Q Is it correct that people from Northern Ireland can travel to a large number of destinations in Europe and pass through Dublin airport?
A Yes, they will not have to self-quarantine but can go to Spain, France and Italy. The fact they may return via Dublin could add another risk.
Q Has the reopening of so many shops, pubs and businesses widened the chances of spread?
A When safety measures are followed, the risk of infection is minimised.
But if the rules are flouted there is more scope for the virus being passed on.
Q Why are there not mandatory rules to quarantine after arrival from abroad? And should close contacts be compelled to be tested?
A Neither is mandatory and unlikely to be unless there may another dangerous surge.
Q Did last weekend's street gatherings have much impact?
A It's too early to say what the impact of the revelries outside pubs seen last weekend will have on infection rates.
Q What about the R number - it's now at or above one?
A If it rises higher than one, it means people infected with the virus are spreading it to others at a rate faster than one-to-one, which could see the disease spiral out of control.
We are told there is no cause for alarm but there is need for caution.