E-cigarettes (electronic cigarettes) have been the most used tobacco product among US youth since 2014, reaching a plateau during the COVID-19 pandemic. Youth e-cigarette use is associated with negative health consequences such as impaired cognitive functioning. For many, the COVID-19 pandemic altered social interactions, harm perceptions, and product availability. This changed the frequency and locations in which youth use e-cigarettes. To better understand youth e-cigarette use, we need more information on factors that can alter e-cigarette use, specifically, how the pandemic changed e-cigarette use among youth. In 2020-2021, we conducted online, individual interviews with 19 youth (aged 13-17) e-cigarette users living in the US to explore how COVID-19 impacted their e-cigarette use. Youth described a progression of e-cigarette use from initial experimentation, regular social use, and ultimately to nicotine addiction demonstrated by individual use in isolation. Many youth initiated e-cigarette use due to influences by friends or family members. Youth discussed progression to social use, with social interactions as an important reason for use and an avenue for expanding one's knowledge of e-cigarettes. After a period of time, youth began to recognize that the social interactions mattered less, suggesting to them that they had become addicted. This realization became more apparent during COVID-19, which changed how youth used e-cigarettes, especially around where use was occurring, health concerns, and use behavior and frequency. In our interviews, youth trajectory began with an initiation with family and friends, progressed to social use, and eventually developed to addiction, at which point social use was no longer the primary motivation for e-cigarette use. Understanding the trajectory of e-cigarette use will allow for effective interventions that reduce harm to youth from e-cigarette use.