LAUSR

Conner et al 1 and Best et al 2 report the results of two longitudinal studies of teenagers in the UK that examined the relationship between vaping an e-cigarette and smoking a cigarette. Similar to studies conducted in the USA,3 4 they both report an association between experimentation with vaping and subsequent experimentation with smoking. Fears that an increase in vaping will lead to an increase in smoking among young people via a ‘gateway’ effect have been used to support greater regulation of vaping products5 or to advocate for continued prohibition of vaping products containing nicotine in countries that do not allow their sale, possession or use by adults.6 Are these reasonable responses to these research findings? Several things should be considered in the interpretation of these studies. 1. A proportion of the young people who try vaping and then smoking would have also tried smoking without trying vaping due to a common liability to experiment with substance use.5 7 2. It is plausible that vaping may increase the likelihood of experimenting with smoking through increased familiarity with a behaviour that resembles smoking and/or curiosity about how the two experiences compare.7 8 But it is unknown how many of those who might try smoking who would not have done so without trying vaping first will then go on to become regular smokers. 3. The baseline waves of these longitudinal studies were conducted in locations and at times when there were no …