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. Tan, DHS, Hull, MW, Onyegbule, SO, Ajiboye, W, Arkell, C, Baril, JG et al.. Canadian guideline on HIV pre- and postexposure prophylaxis: 2025 update. CMAJ. 2025;197 (41):E1374-E1391. doi: 10.1503/cmaj.250511. PubMed PMID:41326046 .
  2. Tan, DHS, Hull, MW, Onyegbule, SO, Ajiboye, W, Arkell, C, Baril, JG et al.. [Not Available]. CMAJ. 2025;197 (41):E1403-E1424. doi: 10.1503/cmaj.250511-f. PubMed PMID:41326041 .
  3. Grewal, R, Lau, C, Kwong, JC, Burchell, AN, Friedman, L, Navarro, C et al.. Characteristics of individuals who received a complete, 2-dose mpox vaccine regimen as part of the public health response to the mpox epidemic in Ontario, Canada. PLOS Glob Public Health. 2025;5 (11):e0005452. doi: 10.1371/journal.pgph.0005452. PubMed PMID:41296795 PubMed Central PMC12654912.
  4. Xi, M, Tan, DHS, Baral, SD, Kugathasan, H, Masucci, L, Skidmore, B et al.. Evolving landscape of economic evaluations of HIV pre-exposure prophylaxis and pre-exposure prophylaxis implementation strategies: a systematic review. J Int AIDS Soc. 2025;28 (11):e70058. doi: 10.1002/jia2.70058. PubMed PMID:41275419 PubMed Central PMC12640620.
  5. Oo, MM, Karabelas-Pittman, S, Hull, M, Grace, D, Lachowsky, NJ, MacPherson, P et al.. Impact of "absolute" versus "relative" HIV risk communication on pre-exposure prophylaxis interest in Canada: a randomized survey. AIDS Care. 2025; :1-12. doi: 10.1080/09540121.2025.2587911. PubMed PMID:41257432 .
  6. Xi, M, Bullock, S, Mendelsohn, JB, Moravan, V, Burchell, AN, Tan, DHS et al.. The impact of Undetectable=Untransmittable and viral suppression on condomless sex among mixed HIV-status couples in Canada. PLoS One. 2025;20 (10):e0332926. doi: 10.1371/journal.pone.0332926. PubMed PMID:41066441 PubMed Central PMC12510518.
  7. Oo, MM, Rudd, M, Shukalek, C, Kishibe, T, Hull, M, Tan, DHS et al.. Diagnostic performance of HIV risk assessment tools for identifying pre-exposure prophylaxis candidates: a systematic review and meta-analysis. EClinicalMedicine. 2025;88 :103487. doi: 10.1016/j.eclinm.2025.103487. PubMed PMID:41018499 PubMed Central PMC12475485.
  8. Hurst, JR, Addo, M, Li, A, Khera, SS, Persaud, R, Bertucci, C et al.. Monkeypox virus shedding despite tecovirimat treatment in a cohort in Toronto, Canada. J Infect Dis. 2025; :. doi: 10.1093/infdis/jiaf471. PubMed PMID:40924858 .
  9. Orkin, C, Paterson, A, Elias, A, Smuk, M, Ring, K, Volny-Anne, A et al.. Establishing shared definitions of virological failure and discontinuation for long-acting injectable cabotegravir and rilpivirine therapy (the CONSENSUS-LAI Study): an international survey and Delphi process. Lancet HIV. 2025;12 (9):e649-e659. doi: 10.1016/S2352-3018(25)00131-6. PubMed PMID:40774264 .
  10. Hurst, JR, Tan, DHS, Li, A, Khera, SS, Persaud, R, Chan, A et al.. Monkeypox Virus Transcriptional Profiles and Host Responses in Skin Lesion Swabs Among Individuals With Human Immunodeficiency Virus. J Infect Dis. 2025;232 (5):e849-e858. doi: 10.1093/infdis/jiaf316. PubMed PMID:40498594 PubMed Central PMC12614975.
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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