The 30-day prevalence for vaping use is about the same as for marijuana. See https://www.drugabuse.gov/drugs-abuse/marijuana (TL;DR: 5.60%, 16.70%, and 22.20% for 8th, 10th, and 12th graders, respectively, for 2018.)

And despite the scary stories, it seems reported vaping use hasn't sharply risen. It peaked in 2015, substantially declined in 2017, and for 2018 seems to have returned to 2015 levels. But overall vaping use has at worst replaced cigarette smoking and possibly accelerated the long-term decline in smoking. A recent study, https://tobaccocontrol.bmj.com/content/early/2018/10/31/toba..., concludes

> If our primary concern is population-level trends in youth and young adult smoking, which we believe is appropriate, then vaping has not shown to be a serious cause for concern, even if the catalyst hypothesis is correct, and it is possible that vaping may be playing a contributing role to the recent steep declines in youth and young adult smoking.

The anti-vaping hysteria is irresponsible and to the extent it ignores the data and creates a boogeyman out of unknowns it's anti-science. Compared to the parade of horribles consequent to tobacco use and even marijuana use, not to mention alcohol and other drugs, nicotine itself should be the least of our worries. And that's before we even consider the efficacy of a ban in terms of preventing teen vaping. (And if we as a community could manage to have an adult conversation about nicotine, like we briefly did for THC, we might appreciate the benefits of nicotine--e.g. that it's used by a significant fraction of adults and teens alike to self-medicate real behavioral and mental health problems.)