There was little evidence that vaping leads to smoking.
http://reason.com/blog/2016/06/27/eu-survey-finds-e-cigarettes-helped-mill
A large survey of Europeans indicates that more than 6 million have quit smoking with the help of e-cigarettes, while more than 9 million have cut back, according to a study recently published by the journal Addiction. “These are probably the highest rates of smoking cessation and reduction ever observed in such a large population study,” says the lead researcher, Konstantinos Farsalinos, a cardiologist at the Onassis Cardiac Surgery Center in Athens. “The European Union data show that the use of electronic cigarettes seems to have a positive impact on public health for two main reasons: 1) High smoking cessation and reduction rates are observed, and 2) electronic cigarette use is largely confined to smokers (current and former), with minimal use by nonsmokers.”
The study, based on responses from 27,460 participants in the Eurobarometer survey, found that 48.5 million citizens of E.U. countries have tried e-cigarettes, while 7.5 million are current vapers. Within the latter group, 35 percent reported that e-cigarettes helped them quit smoking, while 32 percent said they were smoking less thanks to e-cigarettes. Such self-reports are not conclusive, since the study did not independently verify smoking status, smokers who try to quit by vaping are probably different from those who don’t, and it’s possible these outcomes could have been achieved without e-cigarettes. But policy makers and regulators should not lightly dismiss the experiences of millions who say e-cigarettes helped them make changes that dramatically reduced the health hazards they face.
Critics of vaping say the risk that it will lead to smoking in people who otherwise never would have used tobacco products must be weighed against the success stories of people who believe they’d still be smoking if it weren’t for e-cigarettes. But this study found very little evidence of such a risk. Just 0.8 percent of respondents who had ever tried tobacco products said they had tried e-cigarettes first (which does not necessarily mean that the latter led to the former). Only 1.3 percent of never-smokers reported using e-cigarettes with nicotine-containing liquids, and only 0.09 percent did so every day. “In nonsmokers we observed some experimentation with electronic cigarettes, but regular use is minimal,” says one of Farsalinos’ collaborators, Jacques Le Houezec, a neuroscientist at the French National Research Institute for Health and Medical Research. “The concern that electronic cigarettes can be a gateway to smoking is largely rejected by our findings.”