When they thaw the vaccine and prepare it, they only have so much time to use it. For whatever reason, people do not show for their appointments and rather than waste the vaccine, the will give it to people on the stand-by list in order of priority. He got a call late Thurs. and was, apparently, one of the few willing to show up at that hour. So sure, the most vulnerable are the priority, but if gramps and gram won't show....I realize they're supplying vaccines as fast as possible, but not everyone can get one who wants one. So what's the priority? Did Grand Rapids run out of old people? Seems to me, assuming your son doesn't have other co-morbidities at age 23, he should probably be one of the last in line. And of course, your mom should be prioritized.