Trends in where adults buy their e-cigarette supplies: findings from 2016 to 2024 International Tobacco Control (ITC) four country smoking and vaping surveys

BACKGROUND: Little is known about trends in electronic cigarette (EC) purchase sources across countries with different regulations. METHODS: We analysed five waves of the International Tobacco Control Four Country and Vaping (ITC 4CV) survey data from Canada, USA, England and Australia (2016, 2018, 2020, 2022, 2024) comprising representative samples (aged ≥18) who reported vaping ≥weekly, past-month EC purchasing and last purchase source (ie, online, vape shop, other retail places defined as places other than online and vape shops) in ≥1 survey (n=8904). Generalised estimating equations models estimated purchase locations over time within and between countries. FINDINGS: EC purchase locations differed between countries and over time. In Canada, between 2016 and 2018, other retail places decreased by 7.9% (p=0.04); between 2018 and 2020, other retail places increased by 12.1% (p<0.01). In the USA, between 2020 and 2022 online purchasing decreased by 14.4% (p<0.01), while vape shop purchasing increased by 12.4% (p<0.01). In Australia, between 2020 and 2022 online purchasing decreased by 23.6% (p<0.01) while other retail places increased by 22.5% (p<0.01) and increased again between 2022 and 2024 by 15.1% (p<0.01). In 2024, purchasing in vape shops was more common in Canada (61.4%) and the USA (55.0%) compared with England (31.6%) and Australia (21.4%); online purchasing was more common in England (30.8%) than Canada (17.6%), Australia (18.0%) and the USA (11.7%); and purchasing from other retail places was more common in Australia (60.7%) than England (37.6%), the USA (33.3%) and Canada (21.0%). Purchasing from a pharmacy/chemist was rare. INTERPRETATION: EC regulations may influence where consumers can legally be sold EC supplies.