Abstract: Addictive Behaviors 126 (2022) 107170 Contents lists available at ScienceDirect Addictive Behaviors journal homepage: www.elsevier.com/locate/addictbeh Concurrent use of e-cigarettes and cannabis and associated COVID-19 symptoms, testing, and diagnosis among student e-cigarette users at four U. S. Universities Ashley L. Merianos a, *, Alex M. Russell b, E. Melinda Mahabee-Gittens c, Adam E. Barry d, Meng Yang e, Hsien-Chang Lin e a School of Human Services, University of Cincinnati, Cincinnati, OH, USA Department of Health, Human Performance, & Recreation, University of Arkansas, 308 HPER Building, Fayetteville, AR 72703, USA c Division of Emergency Medicine, Cincinnati Children’s Hospital Medical Center, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA d Department of Health and Kinesiology, Texas A&M University, College Station, TX 77843-4243, USA e Department of Applied Health Science, Indiana University School of Public Health - Bloomington, Bloomington, IN, 47405, USA b A R T I C L E I N F O A B S T R A C T Keywords: Electronic nicotine delivery systems Cannabis use College students Introduction: This investigation assessed whether current (past 30-day) electronic cigarette (e-cigarette) and cannabis use was associated with coronavirus disease 2019 (COVID-19) symptomatology, testing, and diagnosis among college student e-cigarette users. Methods: Participants were 18–26-year-old college student e-cigarette users attending four geographically diverse, large U.S. public universities during October-December 2020 (N = 800). Multivariable logistic regres­ sion models explored associations between exclusive e-cigarette use and concurrent e-cigarette and cannabis use and COVID-19 symptoms, testing, and diagnosis. Models controlled for demographics, university site, and cur­ rent use of combustible cigarettes, cigars, and smokeless tobacco. Results: Over half of student e-cigarette users (52.0%) concurrently used cannabis. Compared to exclusive ecigarette users, concurrent e-cigarette and cannabis users were 3.53 times more likely (95%CI = 1.96–6.36) to report COVID-19 symptoms, after adjusting for the covariates. Compared to infrequent exclusive e-cigarette users, infrequent concurrent users (AOR = 4.72, 95%CI = 1.31–17.00), intermediate concurrent users (AOR = 5.10, 95%CI = 1.37–18.97), and frequent concurrent users (AOR = 7.44, 95%CI = 2.06–26.84) were at increased odds of reporting COVID-19 symptoms. Compared to exclusive e-cigarette users, concurrent e-cigarette and cannabis users were 1.85 times more likely (95%CI = 1.15–2.98) to report a COVID-19 diagnosis. Intermediate concurrent users (AOR = 2.88, 95%CI = 1.13–7.35) and frequent concurrent users (AOR = 3.22, 95%CI = 1.32–7.87) were at increased odds of reporting a COVID-19 diagnosis, compared to infrequent exclusive ecigarette users. Conclusions: Concurrent use of e-cigarettes and cannabis may be an underlying risk factor of COVID-19 symp­ tomatology and diagnosis, with more pronounced odds found among intermediate and frequent users. Results highlight the need to educate students about the impacts of e-cigarette and cannabis use on respiratory, immune, and overall health.