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Seth Welles, PhD, ScD

Seth Welles

Epidemiology and Biostatistics
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BA, Biology, Boston University; PhD, Cellular Biology, Boston University; ScD, Epidemiology, Harvard University


Dr. Welles received doctoral training in both cellular/molecular epidemiology at Boston University and viral epidemiology at the Harvard School of Public Health. He conducts research and mentors students in studies of infection and chronic disease, including viral carcinogenesis and HIV/AIDS. His earliest epidemiologic work was focused on studies of immune suppression and adult T-cell leukemia/lymphoma caused by the human T-cell lymphotropic virus type I (HTLV-I). Subsequently, he worked as an epidemiologist and biostatistician with the AIDS Clinical Trials Group to assess the utility of using molecular markers of HIV antiretroviral drug resistance, HIV-1 viral load, and CD4 cell number as prognostic and surrogate markers of clinical disease.

Additionally, Dr. Welles studies psychosocial risk for HIV infection and STDs among sexual minority adults and adolescents. He has conducted random surveys of sexual minority adults at community festivals and at health-clinics to assess demographic and psychosocial determinants of sexual risk-taking in gay and bisexual men.

Sponsored Research:

A Randomized, Double Blind, Phase 2B Study Testing the Efficacy and Safety of AGS-004 (dendritic cell vaccine) on Host Control of HIV Replication during Analytical Treatment Interruption (NIH/NIAID; Role: Co-Investigator)

Long-acting, self-administered HIV therapy with the CCR5 antibody PRO 140 (NIH/NIAID; Role: Co-Investigator)

HCV Cancer Vaccines (PA Department of Health & Human Services; Role: Co-Investigator)

Identification of risk factors for Clostridium difficile infection at Hahnemann University Hospital (Pfizer; Role: Co-Investigator)

Establishing Evidence for Peer Group Support and Asset Building Among Families with Young Children on TANF: Ensuring Fidelity & Producing Indicators (Annie E. Casey Foundation; Role: Co-Investigator)

Recent Student Projects


  • Health-Related Quality of Life in the Era of Highly Active Anti-Retroviral Therapy in a large United States Military Cohort of Individuals Living with Human Immunodeficiency Virus

  • Evaluation of Treatment Adherence Patterns among Members of the HIV Natural History Cohort Study, an RV168 Substudy
  • On Individual and Community-Level Determinants of Pertussis and Flu Incidence and Vaccination

  • To Be or Not To Be: Men Who Have Sex with Men and Bayesian Correction of Misclassification

  • The Role of Hormone Therapy on Cardiovascular Disease among Transgender Men and Women in Philadelphia


  • Youth Asthma Epidemiologic Surveillance in Croix-des-Bouquets, Haiti

  • An Investigation of Body Art and Blood Borne Viruses in Philadelphia
  • Comparison of Confirmed and Unconfirmed Antibody-Positive Hepatitis C Cases in Philadelphia

  • Evaluating the Effectiveness of the “Take Control Philly” Condom Mailing Distribution Program
  • Attitudes Towards Sexual Minorities and HIV among Residents of the Russian Federation

Research Interests

    • Cancer
    • Clinical Trials
    • Community Engaged Research
    • Data Analysis Methods
    • Global health or International helath
    • Health Disparities
    • Infectious Disease
    • Mental health and Behavioral health
    • Reproductive or Sexual Health
    • Statistical Modeling
    • Substance use
    • Violence and Trauma


    LeVasseur MT, Goldstein ND, Welles SL. A public health perspective on HIV/AIDS in Africa: Victories and unmet challenges.  Pathophysiology 2014; 21: 237-56.

    Baliban SM, Michael A, Shammassian B, Mudakha S, Khan AS, Cocklin S, Zentner I, Latimer BP, Bouillaut L, Hunter M, Marx P, Sardesai NY, Welles SL, Jacobson JM, Weiner DB, Kutzler MA. An Optimized, Synthetic DNA Vaccine Encoding the Toxin A and Toxin B Receptor Binding Domains of Clostridium difficile Induces Protective Antibody Responses In Vivo. Infect Immun 2014; 82:4080-91

    Sweet T, Polansky M, Welles SL. Mediation of HIV/STI Risk by Mental Health Disorders Among Persons Living in the United States Reporting Childhood Sexual Abuse. JAIDS 2013; 62:81-9

    Sweet T, Welles SL.  Associations of sexual identity or same-sex behaviors with history of childhhod sexual abuse and HIV/STI risk in the United States. JAIDS 2012; 59:400-8.

    Politch JA, Mayer KH, Welles SL, O'Brien WX, Xu C, Bowman FP, Anderson DJ. Highly active antiretroviral therapy does not completely suppress HIV in semen of sexually active HIV-infected men who have sex with men. AIDS 2012; 26:1535-43.