so you reckon we should go for level 5?The deceleration in Dublin shows that people in Dublin have generally listened to the message being put across, limit contacts etc. Also the fact that Dublin went to level 3 and therefore all indoor pubs and restaurants stopped happening (mostly pubs of course) helps a lot.
I would think that the 19-24 age group is a particular problem because it's the exact age group that would have the hardest time not socialising in groups, plus bringing universities back would have encouraged this as well. I think people in this age group are probably much more likely to act on impulse regardless of what the rules say, they're just old enough to be adults and in control of their own life but still young enough to not really feel much responsibility generally.
Finally, the household spreading numbers are somewhat unreliable I feel. Not denying there is probably a lot of spreading from people just visiting each other's houses, but the virus has to get into houses in the first place, and surely a lot of that happens from schools and (pre level 3) pubs etc.; how many people diagnosed as 'household' were actually having a pint somewhere the week before and wouldn't admit it to the track and trace process? I'd imagine it might be something like 5/10 would admit it, the other half would say they don't know where they could have got it from.