A resurgence of e-cigarette use among adolescents and young adults late in the COVID-19 pandemic

Background Early in the COVID-19 pandemic, e-cigarette use significantly declined among young people due, in part, to losing access through social sources. As the pandemic progressed, adolescents and young adults gained opportunities to resume contact with peers. This study sought to determine whether e-cigarette use has returned to pre-pandemic levels among adolescents and young adults. Methods Data were drawn from a cross-sectional weekly survey of adolescents (aged 15–17) and young adults (aged 18–24) (N = 37,331). Logistic regression analyses measured odds of past 30-day e-cigarette use among respondents surveyed (a) late in the pandemic (April 2021—April 2022) compared to early in the pandemic (March–July 2020) and (b) late in the pandemic (August–December 2021) compared to prior to the pandemic (August–December 2019). Results The odds of current e-cigarette use were significantly higher later in the COVID-19 pandemic (April 2021–April 2022), compared to its initial months (March–July 2020) (OR:1.27, 95% CI: 1.17–1.38; p = 0.001). There was no significant difference in the odds of e-cigarette use for youth and younger adults late in the pandemic (August–December 2021) compared to the same time period prior to the pandemic (August–December 2019), but odds were greater for young adults aged 21 years or older (OR:1.16; 95% CI: 1.01–1.32; p = 0.030). Conclusions E-cigarette use has returned to pre-pandemic levels among adolescents and young adults. Young adults over age 21 are more likely to use e-cigarettes than young adults of the same age surveyed prior to the pandemic. Findings have implications for targeted e-cigarette prevention and cessation efforts.

are as likely to report current e-cigarette use compared to those surveyed during a comparable time span prior to COVID-19 (July 31-December 31 2019).

Methods
The study used data from a continuous cross-sectional online panel survey of adolescents (aged [15][16][17] and young adults (aged 18-24 years). A total of 37,331 respondents were surveyed between July 31, 2019 and April 26, 2022. Approximately 280 unique respondents were sampled per week using sampling quotas to achieve equal proportions of each age group and sex. Data were weighted to be nationally representative using demographic characteristics according to the US Census. The study received approval from the Advarra Institutional Review Board.
Data were aggregated by month to determine the monthly prevalence of e-cigarette use in the sample. Logistic regression models were used to determine whether an observed change in past 30-day e-cigarette was significantly greater among adolescents and young adults in later months of the study period. Each respondent was surveyed once during the study period, thus the pre-post comparisons between responses were unpaired and aggregated for each time period.
Based on previous research demonstrating differences in COVID-19-related trends in ecigarette use by age, models were stratified by age group (15)(16)(17) years, 18-20 years, and 21-24 years) [6]. Current e-cigarette use, defined as use on at least 1 day during the past 30 days, was the outcome. Other covariates included race/ethnicity (non-Hispanic white, non-Hispanic Black, non-Hispanic and other race, or Hispanic), a validated measure of subjective financial situation to serve as a proxy for socioeconomic status, sensation-seeking score, and sex [11]. We used a fixed effect for respondent's state of residence to control for variations in state-level e-cigarette policies and other interventions (e.g., age restrictions, anti-vaping mass media campaigns) and COVID-19 responses (e.g., vaccination roll-out schedules and uptake, school closures).

Results
Approximately one-quarter (27.8%) of the sample surveyed during the study period (August 2019 to April 2022) were between the ages of 15 and 17 years, slightly less than one-third (31.1%) were aged 18 to 20, and the remainder (41.1%) were aged 21 to 24. Half (50.7%) of the sample was male. Slightly more than half (57.2%) were white and non-Hispanic. One-quarter (25.0%) identified as having Hispanic ethnicity. Black non-Hispanic and other non-Hispanic respondents made up smaller proportions of respondents (12.9% and 7.1%, respectively). The majority (59.4%) reported that their financial circumstances met their basic needs with a little left over, or to live comfortably. One-quarter (27.3%) of the sample, aggregated over the course of two years, were current e-cigarette users (Table 1).
For the first analyses testing the odds of e-cigarette use late in the COVID-19 pandemic compared to the pandemic's early months, significant differences in e-cigarette use were found according to the phase of the pandemic in which respondents were interviewed (Table 2). Respondents surveyed from April 2021 to April 2022 had significantly higher odds of e-cigarette use compared to those surveyed early in the pandemic (March-July 2020) (OR: 1.27, 95% CI: 1.17-1.38, p<0.001). This finding remained significant in models stratified by each age group. For adolescents aged 15-17, the odds of e-cigarette use were 1.22 (95% CI: 1.01-1.49; p = 0.043) late in the pandemic compared to its early stages; for those aged 18-20 years, the odds were 1.41 (95% CI: 1.21-1.64, p<0.001); and for those aged 21-24, the odds were 1.18 (95% CI: 1.05-1.33, p = 0.007) ( Table 2).
For the second analyses testing the odds of e-cigarette use late in the COVID-19 pandemic compared to a similar time span before the pandemic, there was no significant difference in ecigarette use during the late-COVID-19 period (August-December 2021) compared to the same time span prior to the pandemic (August-December 2019) ( Table 3). These findings were consistent in models stratified among underage respondents (aged 15-17 and 18-20 years). However, the odds of e-cigarette use among young adults aged 21-24 was significantly higher during the August-December 2021 time period compared to the same age group surveyed in the August-December 2019 time period (OR: 1.21, 95% CI: 1.06-1.38; p = 0.006).

Discussion
The findings of this study indicate that e-cigarette use has returned to pre-COVID-19 prevalence rates among young people aged 15-24 years old in the United States. Among young adults aged 21-24 years, evidence indicates that the likelihood of e-cigarette use is significantly higher as compared to the period before the pandemic. In 2019, immediately prior to the COVID-19 pandemic, e-cigarette use had reached unprecedented rates of use among young people in the United States [3,4].
These findings are observed as young people increase their engagement in social activities and attendance for in-person schooling with the progression of the COVID-19 pandemic in the United States. While previous research indicated that younger people reported reduced ecigarette access due to COVID 19 restrictions, young adults did not experience the same access issues [6]. As adolescents and college-enrolled young adults return to school, they once again encounter peer e-cigarette use, which increases accessibility and can serve to normalize vape PLOS ONE E-cigarette use among adolescents and young adults late in the COVID-19 pandemic use behaviors. Other research has found that young e-cigarette users report increasing use to cope with stress [7]; those emerging from the pandemic may encounter new stressors following several years of remote learning and working. Furthermore, e-cigarette manufacturers have continued to market products throughout the pandemic, including messages with youth appeal and/or specific to COVID-19 (e.g., health reassurances) [12]. Exposure to e-cigarette marketing has been shown to be a factor in initiation and progression to regular use of these products among young people [13][14][15][16][17].
Evidence is emerging on the effectiveness of anti-vaping interventions that denormalize ecigarette use among young people, contributing to a reduced risk of initiation and increased likelihood of quitting [18,19]. Greater opportunities for social contacts among adolescents and young adults are to be expected as society continues to adapt to and recover from the COVID-19 pandemic, and with them the increased potential to obtain e-cigarettes from social contacts and observe e-cigarette use behaviors among peers. Health communication efforts targeting adolescents and young adults that portray e-cigarettes as socially unacceptable among important others, including peers, is increasingly relevant and critical.  Schools and colleges can take steps to reduce e-cigarette use on campus through policy implementation, though the presence of a policy alone may not be sufficient [20]. Schools need to train staff to be aware of emerging products, and how to intervene in non-punitive ways to reduce underage access and use [21]. Additionally, flavor policy restrictions at the local level can play a role in reducing retail access to flavored e-cigarettes, thus reducing the likelihood of underage use [22]. Taken together, these policies both in the school environment and at the local level can limit underage access to e-cigarettes.

Limitations
Despite this study's many strengths, there are several limitations. First, despite sampling quotas and survey weights applied to the data, the survey was conducted among a convenience sample and cannot be considered nationally representative. Estimates of the prevalence of e-cigarette use may therefore be biased to an unknown extent and are not directly comparable to nationally representative samples surveyed using other methods (e.g., classroom-based surveys). However, the continuous tracking methodology and large sample size strengthen the study's internal validity and allow precision when comparing segments of the study population surveyed during different points in time. Second, the survey did not include a measure of respondents' sources for e-cigarettes prior to the COVID-19 pandemic, limiting conclusions about the relative role of retail and social sources played in adolescents and young adult access to e-cigarette products before, compared to during, the pandemic. Future research comparing information on sources of e-cigarettes pre-and post-COVID-19 can help create relevant policy interventions to best reduce access. Third, although research suggests that youth and young adults were using e-cigarettes to cope with stress during the COVID-19 pandemic [7], the study did not control for respondents' mental health status due to the lack of comparable measures of mental health on the survey over time. We therefore cannot use the study findings to draw conclusions about the role of mental health in the observed greater likelihood of e-cigarette use later in the pandemic. The interaction between the COVID-19 pandemic, youth and young adult mental health, and trajectories of nicotine and other substance use warrants further research, ideally using longitudinal samples followed prior to and beyond the COVID-19 pandemic.

Conclusions
Renewed attention must be paid to the re-emerging epidemic of e-cigarette use among young people. The temporary decline in e-cigarette use during the COVID-19 pandemic [6], followed by the increase observed in the current study, is indicative of the powerful role of social influences and points of access on e-cigarette use among adolescents and young adults. Evidencebased tobacco control efforts are urgently needed, including further restrictions on sales of ecigarettes with youth appeal (e.g., flavored products), as well as targeted public health campaigns and cessation services, to encourage the next generation to reject tobacco, vaping and nicotine.