Vallone DM, et al. - In this nationally representative cohort study, researchers calculated the prevalence, patterns, and factors correlated over time with electronic cigarette (e-cigarette) use among adolescents and younger adults in the United States. They involved two nationally representative longitudinal samples of adolescents and younger adults aged 15 to 34 years from the Truth Longitudinal Cohort, a national, probability-based cohort. In this cohort, they selected people through address-based sampling, and subsamples were recruited from a probability-based online panel. They recruited a sum of 14,379 people (mean [SD] age, 24.3 [0.09] years; 8142 female [51.0%]) were included in wave 7 and 12,114 (mean [SD] age, 24.5 [0.10] years; 6,835 female [50.1%]) in wave 8. The findings suggested that the e-cigarette device JUUL seems to be correlated with the youth e-cigarette epidemic, bringing new users and promoting frequent use with their highly addictive nicotine content and appealing flavors. Findings from this study demonstrate the critical need for increased regulation of e-cigarette products at the federal, state, and local levels.