Prevention interventions may reduce e-cigarette ever use while cessation-focused efforts likely reduce current adolescent usageInterventions May Help Reduce E-Cigarette Use in Young People

Rationale The prevalence of e‐cigarette use has recently increased globally amongst children and adolescents. In response to this increase and emerging evidence about the potential harms of e‐cigarettes in children and adolescents, leading public health organisations have called for approaches to address e‐cigarette use. Whilst evaluations of approaches to reduce uptake and use regularly appear in the literature, the collective long‐term benefit of these is currently unclear. Objectives The co‐primary objectives were to: (1) evaluate the effectiveness of interventions to prevent e‐cigarette use in children and adolescents (aged 19 years and younger) with no prior use, relative to no intervention, waiting‐list control, usual practice, or an alternative intervention; and (2) evaluate the effectiveness of interventions to cease e‐cigarette use in children and adolescents (aged 19 years and younger) reporting current use, relative to no intervention, waiting‐list control, usual practice, or an alternative intervention. Secondary objectives were to: (1) examine the effect of such interventions on child and adolescent use of other tobacco products (e.g. cigarettes, cigars, chewing tobacco and pouches); and (2) describe the unintended adverse effects of the intervention on individuals, or on organisations where such interventions were being implemented. Search methods We searched CENTRAL, Ovid MEDLINE, Ovid Embase, Ovid PsycINFO, EBSCO CINAHL and Europe PMC on 1st September 2025. Additionally, we searched two trial registry platforms (WHO International Clinical Trials Registry Platform; ClinicalTrials.gov), and reference lists of relevant systematic reviews. We contacted corresponding authors of articles identified as ongoing studies. Eligibility criteria We included randomised controlled trials (RCTs), including cluster‐RCTs, factorial RCTs, and stepped‐wedge RCTs. To be eligible, the primary targets of the interventions were children and adolescents aged 19 years or younger. Interventions could have been conducted in any setting, including the community, school, health services, or the home, and must have sought to influence children or adolescent (or both) e‐cigarette use directly. Studies with a comparator of no intervention (i.e. control), waiting‐list control, usual practice, or an alternative intervention not targeting e‐cigarette use were eligible. Two review authors independently screened the titles and abstracts of references, with any discrepancies resolved through consensus or a third reviewer. Outcomes The critical review outcome was e‐cigarette use in children and adolescents aged 19 years or younger. We included measures to assess the effectiveness of interventions to: prevent child and adolescent e‐cigarette use (including measures of e‐cigarette use amongst those who were never‐users); and cease e‐cigarette use (including measures of e‐cigarette use amongst children and adolescents who were current e‐cigarette users at baseline). We included data measured at least six months post‐baseline. Outcomes were current use (defined as use in the past 30 days), ever use (defined as any lifetime use) and adverse effects. Risk of bias Risk of bias for all included studies was assessed using the Cochrane RoB 2 tool. We applied this tool to the critical and important review outcomes from each included study to assess and rate each outcome as low, some concerns or high for all relevant domains. Synthesis methods Pairs of review authors independently extracted information from the included studies, with any discrepancies resolved through consensus or a third reviewer when required. Meta‐analyses were conducted using a random‐effects model where data were suitable for pooling, with two prevention studies measuring e‐cigarette use pooled. Studies and outcomes unsuitable for pooling in meta‐analyses were instead summarised narratively. Included studies We identified three studies with 10,510 participants as eligible for inclusion. A further 30 studies were identified as ongoing and five are awaiting classification and likely to be eligible for a future update. Two studies employed a cluster‐RCT design to test the effectiveness of school‐based interventions to prevent adolescent e‐cigarette use, with one study judged to have ‘some concerns’ for the overall risk of bias for the e‐cigarette ever‐use outcome and the other study judged as 'high risk'. The remaining study employed an RCT design to test the effectiveness of a community‐based intervention (delivered via text‐messages) to support adolescents to cease e‐cigarette use. We judged the overall risk of bias as low for this study which reported an e‐cigarette current‐use outcome. Included studies were conducted in the United States, Australia and Sweden. Synthesis of results For the critical outcome of e‐cigarette ever use, a meta‐analysis of two studies (one high risk of bias, one some concerns) found that prevention interventions may prevent ever use, relative to usual care, although evidence is very uncertain (RR 0.94, 95% CI 0.89 to 0.99; 2 studies; 5306 participants; random‐effects model; very‐low certainty evidence). The certainty of evidence in this effect was downgraded due to risk of bias, indirectness and imprecision. One study reporting a prevention intervention reported no adverse effects. For the critical outcome of e‐cigarette current use, one study reported that a cessation‐focused intervention is likely to reduce adolescent current use of e‐cigarettes (RR 0.73, 95% CI 0.65 to 0.82; 1 study, 1064 participants; moderate‐certainty evidence). The certainty of evidence in this effect was downgraded due to indirectness. The cessation intervention did not report on adverse effects of the intervention. Authors' conclusions Given only three randomised studies were included in the review, there is limited evidence, of very low‐to‐moderate‐certainty, that interventions may be effective in preventing or ceasing adolescent e‐cigarette use. As findings of the 30 ongoing studies are published, certainty of evidence of effects may improve. Until then, the findings of this review should be considered together with evidence from studies employing other trial designs not eligible for inclusion in this review to guide actions to prevent or cease e‐cigarette use. This is a living systematic review. We search for new evidence every month and update the review when we identify relevant new evidence. Funding This review was supported by the NHMRC Centre for Research Excellence (No. APP1153479) – ‘the National Centre of Implementation Science’. NHMRC also provides support for the editorial and author support function of Cochrane Public Health. Registration This review is registered in the Cochrane Database of Systematic Reviews. The protocol (https://doi.org/10.1002/14651858.CD015511) and previous version of the review (https://doi.org/10.1002/14651858.CD015511.pub2) are published in the Cochrane Library. PICOs PICOs Population Intervention Comparison Outcome