Modelling the potential impacts of limiting vaping product sales to pharmacies

Background: Vaping rates are increasing globally. Restricting vaping products' access may result in net population health loss if youths who vape switch to smoking, or net gain if it promotes cessation among people who smoke. We used simulation modelling to assess how two vaping restriction policies - over-the-counter (OTC) pharmacy access or prescription-only access via general practitioners - might impact vaping and smoking rates in Aotearoa New Zealand (A/NZ). Methods: We adapted an established Markov model of smoking and vaping, linked to a proportional multistate lifetable, to simulate the A/NZ population from 2023 to 2044. Three business-as-usual (BAU) scenarios (low', medium' and high' vaping) were informed by youth vaping trends. Intervention impacts were derived from prior research and expert elicitation. Results: Compared with the medium BAU scenario with 50% vaping among 18-24-year olds by 2044, restricting to OTC pharmacy access reduced vaping prevalence by 6% and increased health-adjusted life years (HALYs). Only under the high' BAU scenario (60% vaping) did interventions marginally increase smoking (2% for OTC). Both interventions averted premature deaths and produced HALY gains. Interpretation: Our model suggests modest reductions in vaping prevalence and net health gains from the OTC pharmacy policy, with minor benefits from a prescription-only approach. These findings underscore the importance of balancing the potential smoking cessation benefits of vaping with the need to curb youth uptake. Future research is required to better understand how vaping restriction policies could impact vaping and smoking dynamics in A/NZ, in particular, considering how illicit supply may impact policy effectiveness.