AIMS: To synthesize and describe the evidence from among young people and adults to assess: (i) what interventions have been effective in changing vaping harm perceptions; and (ii) to what extent vaping harm perceptions predict any changes in vaping and smoking behaviours.

METHODS: Systematic review searching five databases (Embase, PsycINFO, Medline, CINAHL, Scopus) from January 2007 to January 2023. Eligible studies reported quantitative data with >1 time point among young people (sample majority aged <18 years) or adults (sample majority aged ≥18 years). Interventions were considered if they communicated vaping harms, categorized as relative (vaping vs smoking) or absolute (vaping vs not vaping). Outcomes were changes in: (i) vaping (absolute, relative) or nicotine harm perceptions; (ii) vaping or smoking behaviours. Evidence was synthesized narratively.

RESULTS: Eighty-five articles were included, of which 46 assessed interventions to change vaping harm perceptions and 39 assessed associations between harm perceptions and subsequent vaping/smoking behaviours. All studies among young people and most among adults were from the USA. Interventions aimed at young people typically communicated that vaping and nicotine are harmful/addictive (absolute harms), often in the form of educational programmes and media campaigns. Interventions aimed at adults typically communicated that vaping is harmful but less harmful than smoking (relative harms), often via written materials and educational workshops. In addition to methodological and analytical heterogeneity, risk of bias was high; hence findings should be interpreted with caution. Generally, interventions appeared to be effective in changing perceptions that reflected the intervention content among young people (12/14 studies) and adults (24/32 studies), at least in the short-term (38/46 studies only assessed the outcome pre- and immediately post-intervention). Interventions communicating that vaping is harmful and addictive (absolute harms) increased perceptions that vaping is harmful and addictive among young people (12/14) and adults (16/23 studies) and also increased the misperception that vaping is as harmful as smoking (relative harm) among young people (2/2 studies) and adults (5/8 studies). There was also some evidence that both absolute and relative harm perceptions predicted vaping and smoking behaviours, such that perceiving vaping as harmful deterred vaping among both young people (8/9 studies) and adults (4/7 studies), while misperceiving vaping as equally/more harmful than smoking prevented adults from quitting smoking (5/6 studies).

CONCLUSIONS: Interventions to change vaping harm perceptions appear to be effective. Vaping harm perceptions appear to predict vaping and smoking behaviours.