Health economists warned that taxes on e-cigarettes and vape products alone would not be enough to keep teenagers from using other risky tobacco products such as regular cigarettes.

“Our study is now part of a growing body of evidence that different types of policies designed to curb e-cigarette use, while they are generally effective in doing that, they have this unintended consequence of driving people back to a more harmful nicotine delivery system: traditional cigarettes,” said Charles Courtemanche, a health economist at the University of Kentucky and co-author of this month’s report on whether the United States should put a blanket tax on vaping products.