Vaping bans: How one health crisis prompted a crackdown on another

Some promising trends fall short of real progress. Vaping – once considered safer than cigarettes – has emerged as a public health harm for teens and adults. Has the dearth of research sent solutions up in smoke?

The online vape store looks legitimate: It warns away those under 21; a customer chat box pops up when you open the home page; there are online coupons, even a Black Friday sale, for the cartridges filled with marijuana ingredients.

But you can’t pay with credit cards, only cash transfers (Western Union or...