The affect on cases would be due to less drunken no-distance maintained socializing, there is definitely less of that going on. The roads are vrek quiet when I patrol after midnight on a Saturday or Sunday morning, There will definitely be less serious car crashes during that time thus. I recall like something like 25% of all fatal crashes occur from 21:00 to 5:00.
That is assuming that people going out for drinks are infected and spreading. Not sick at home.