National studies in the United Sates indicate that infrequent use of e-cigarettes among adolescents and young adults (“youth”) is extremely common. For example, the most recent national data that reports on use frequency indicates that, among high school students using e-cigarettes, the majority (60.6%) use 1–19 days per month (Park-Lee et al., 2021). Similarly, among young adults who use e-cigarettes, 27.6% use 3 or fewer days each month (Parker and Villanti, 2019). It is generally assumed that most of these infrequently-using youth are on a trajectory toward escalating use. Yet little is known about the proportion of young people who increase in their use frequency. Further, no research has examined how many youth sustain their infrequent use—as compared to escalating in use or stopping e-cigarettes use altogether.

The e-cigarette trajectories of youth are only beginning to be understood, and the early studies on this topic generally indicate that many youth persist in their e-cigarette use behavior (Blank et al., 2023, Mantey et al., 2022, Stanton et al., 2023, Vogel et al., 2019). One study observed a change in daily e-cigarette use from 14.5% to 29.8% over a 12-month period (Vogel et al., 2019). Although daily use is a high threshold to be considered “frequent use” for youth, the study does suggest that use escalation could be occurring among a substantial proportion of youth who vape infrequently. Unfortunately, the majority of youth trajectory studies tend to examine “e-cigarette users” as a whole, heterogenous group, making it difficult to distinguish the trajectories of those who use frequently versus infrequently. Youth who vape infrequently appear to be a varied group even among themselves; one study found that a cluster of youth using e-cigarettes labeled “persistent infrequent users” was too unstable in latent class models to pursue in further analyses (Stanton et al., 2023). Thus, little is known about the trajectories of youth who vape infrequently.

Additionally, research on the predictors of youth e-cigarette trajectories, especially among those using infrequently, is still in its infancy. A recent review (Short and Cole, 2021) indicated that younger age, male gender, use of cigarettes or other substances, and greater e-liquid nicotine concentrations were all associated with the escalation of e-cigarette use among adolescents. It is unclear, however, if these factors are also associated with escalation among youth who use infrequently.

The future outcomes of youth who vape infrequently—particularly, whether they escalate or decline in their use—has important implications for public health. Nicotine is an addictive substance, and e-cigarettes containing nicotine have the ability to establish nicotine dependence (U.S. Department of Health and Human Services, 2016). As a consequence, youth who become addicted to the nicotine in e-cigarettes may continue in their e-cigarette use and also transition to the use of other tobacco products, such as cigarettes (Berry et al., 2019, Keller-Hamilton et al., 2021, Watkins et al., 2018). The constituents of e-cigarettes are also known to be harmful or potentially harmful (Alshareef and Omaye, 2021, American Cancer Society, 2022, Canistro et al., 2017), meaning that prolonged e-cigarette use may increase the risk of negative long-term outcomes such as cancer and heart disease. Whether those who use e-cigarettes infrequently are at risk for these consequences, and what prevention approaches may be necessary, can only be understood once the correlates and outcomes of infrequent e-cigarette use are better established.

The purpose of this study was to examine youth who use e-cigarettes infrequently. We wished to distinguish the correlates of infrequent e-cigarette use (i.e., how do they compare to youth who vape frequently or not at all?), their outcomes (in particular, who escalates in their use?), and the predictors of those outcomes (i.e., what factors predict the likelihood of escalation?). These questions were examined among a sample of adolescents and young adults in Ohio. The correlates and predictors we examine include both individual-level factors characterizing our participants (e.g., sociodemographic factors, risk perceptions, nicotine addiction) but also interpersonal-level factors that characterize the social context in which participants are embedded (e.g., peer and family use, device sharing).