Darrell Tan

MD, FRCPC, PhD

Scientist

Biography

Dr. Darrell Tan is an infectious diseases physician, clinician-scientist and Canadian Institutes of Health Research (CIHR) New Investigator whose research focuses on clinical trials in human immunodeficiency virus (HIV) prevention and HIV/sexual transmitted infection (STI) co-infection. As Director of the University of Toronto Clinical Research Unit on HIV Prevention and co-leader of the CIHR Canadian HIV Trials Network Biomedical Prevention Working Group, he is leading multiple efforts to optimize the implementation of HIV pre- and post-exposure prophylaxis (PrEP and PEP) in Canada. These include Canada’s first demonstration project of daily oral TDF/FTC-based PrEP in Toronto MSM, the development of national Clinical Practice Guidelines on PEP & PrEP use, exploration of the relationship between syndemic health problems and clinical outcomes of PEP & PrEP, studies of nurse-led PEP & PrEP, and evaluations of novel antiretroviral PEP regimens.

Additional research interests are in the interaction between HIV and common co-infections such as herpes simplex virus type 2 (HSV-2) and syphilis, and the role of systemic inflammation in driving clinical outcomes in people living with HIV. He is also Co-Principle Investigator on two CIHR-supported multicentre randomized control trials including the a trial of anti-herpes medication for attenuating HIV disease progression, and a trial of enhanced syphilis screening in HIV-positive men.

Recent Publications

  1. McGarrity, MW, Lisk, R, MacPherson, P, Knox, D, Woodward, KS, Reinhart, J et al.. Hepatitis C Virus Seroprevalence, Incidence, and Screening Patterns in Ontario Preexposure Prophylaxis Users. Open Forum Infect Dis. 2025;12 (1):ofaf014. doi: 10.1093/ofid/ofaf014. PubMed PMID:39877400 PubMed Central PMC11773187.
  2. Xiu, F, Doyle, CM, Anato, JLF, Knight, J, Wang, L, Cox, J et al.. Impact of interventions on mpox transmission during the 2022 outbreak in Canada: a mathematical modeling study of three different cities. Int J Infect Dis. 2025;153 :107792. doi: 10.1016/j.ijid.2025.107792. PubMed PMID:39848438 .
  3. McGarrity, MW, MacPherson, P, Li, A, Naccarato, M, Anderson, P, Tan, DHS et al.. Intracellular tenofovir-diphosphate concentrations in HIV pre-exposure prophylaxis users who underwent bariatric surgery. HIV Med. 2025; :. doi: 10.1111/hiv.13759. PubMed PMID:39812218 .
  4. Tan, DHS, Antinori, A, Eu, B, Galindo Puerto, MJ, Kinder, C, Sweet, D et al.. Weight and metabolic changes with long-acting cabotegravir and rilpivirine or bictegravir/emtricitabine/tenofovir alafenamide. J Acquir Immune Defic Syndr. 2024; :. doi: 10.1097/QAI.0000000000003584. PubMed PMID:39676239 .
  5. Daroya, E, Wells, A, Gaspar, M, Sinno, J, Hull, M, Lachowsky, NJ et al.. Perceptions, experiences and concerns with sexually transmitted infections among current and former PrEP users: a longitudinal qualitative study of gay, bisexual and queer men in Canada. Sex Health. 2024;21 :. doi: 10.1071/SH23195. PubMed PMID:39531372 .
  6. Oo, MM, Shukalek, C, Kishibe, T, Hull, M, Tan, DHS. HIV risk assessment tools for identifying individuals who could benefit from pre-exposure prophylaxis: a systematic review protocol. BMJ Open. 2024;14 (11):e090565. doi: 10.1136/bmjopen-2024-090565. PubMed PMID:39515851 PubMed Central PMC11552022.
  7. Brisson, J, Balasa, R, Bowra, A, Hill, DC, Doshi, AS, Tan, DHS et al.. Motivations for enrollment in a COVID-19 ring-based post-exposure prophylaxis trial: qualitative examination of participant experiences. BMC Med Res Methodol. 2024;24 (1):267. doi: 10.1186/s12874-024-02394-0. PubMed PMID:39501157 PubMed Central PMC11536907.
  8. Zhabokritsky, A, Klein, M, Harris, M, Loutfy, M, Guillemi, S, Tan, DHS et al.. Prevalence and Correlates of Frailty Among Older Adults Living With HIV in the CHANGE HIV Cohort. J Acquir Immune Defic Syndr. 2024;97 (3):226-231. doi: 10.1097/QAI.0000000000003485. PubMed PMID:39431506 PubMed Central PMC11458104.
  9. Tan, DHS, Awad, A, Zygmunt, A, Murray, J, Warshafsky, D, Mishra, S et al.. Community Mobilization to Guide the Public Health Response During the 2022 Ontario Mpox Outbreak: A Brief Report. Open Forum Infect Dis. 2024;11 (Suppl 2):S129-S132. doi: 10.1093/ofid/ofae195. PubMed PMID:39415827 PubMed Central PMC11476808.
  10. Rudd, M, McGarrity, M, Lisk, R, MacPherson, P, Knox, D, Woodward, K et al.. Reported Side Effects and Adherence of Daily HIV Pre-Exposure Prophylaxis Users in Ontario, Canada: An Analysis of the Ontario Pre-Exposure Prophylaxis Cohort Study. AIDS Patient Care STDS. 2024;38 (9):382-392. doi: 10.1089/apc.2024.0144. PubMed PMID:39284166 .
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Affiliations & Other Activities

  • Clinician-Scientist, Department of Medicine, St. Michael’s Hospital
  • Assistant Professor, Department of Medicine, University of Toronto
  • Assistant Professor, Institute of Health Policy, Management & Evaluation, University of Toronto
  • Director, HIV Prevention Clinical Research Unit, University of Toronto
  • Affiliate Scientist, Toronto General Research Institute