[6] Montaner's shift to HIV research began when he encountered AIDS patients with Pneumocystis carinii pneumonia while completing his training in pulmonary medicine.
[5] He participated in and led a series of studies on the role of adjunctive corticosteroids in treating Pneumocystis carinii pneumonia (PCP) patients.
[5] The approach of treating immunosuppressed patients with steroids, which are anti-inflammatory drugs, was unorthodox at the time but Montaner pursued this strategy as he "believed [HIV] was a matter of immune dysregulation as much as suppression.".
[5][11] At the XI International AIDS Society-USA (IAS-USA) Conference in 1996, Montaner presented the findings of the INCAS group, which consisted of HIV-positive cohorts in Italy, Netherlands, Canada, Australia and the United States.
The study also reported a decrease in viral load of less than 20 HIV RNA copies per mL of blood in some patients in the triple therapy group.
"[6] In 1998, the results of the INCAS randomized double-blind clinical trial examining a combination of Nevirapine, Didanosine and Zidovudine as treatment for HIV-positive patients was published in the Journal of the American Medical Association.
[2][5] In 2005, Montaner and his colleagues published a study in The Journal of Infectious Diseases characterizing the development of antiretroviral resistance among a cohort of 1191 initially antiretroviral-naïve HIV positive British Columbians.
[14] The results indicated that a high baseline plasma viral load, poor adherence and the inclusion of non-nucleoside reverse-transcriptase inhibitors (NNRTIs) in the initial drug cocktail were all predictors of development of antiretroviral resistance.
[2][5] The Treatment as Prevention strategy is based on the premise that administering HAART to all medically eligible HIV positive individuals will decrease transmission rates.
Centre for Excellence in HIV/AIDS published an article in The Lancet promoting early and global access to HAART treatment as a strategy not just to decrease mortality and progression to AIDS, but also as a method of reducing HIV transmission.
[17] HAART treatment has been found to reduce viral load to undetectable levels in the female genital tract, semen and blood.
[17] Based on data from Taiwan and British Columbia, Montaner and his colleagues posited that approximately a 50% reduction in HIV transmission could be attributed to widespread HAART adherence.
"[21] Montaner cited the findings of the landmark study HPTN 052, that HAART use can reduce HIV transmission by 96% in sero-discordant heterosexual couples, as compelling evidence for implementing the "Treatment as Prevention" Strategy.
[23] Currently, in British Columbia, Montaner has a role in the largely defunct Seek and Treat for Optimal Prevention of HIV/AIDS (STOP HIV/AIDS) program with assistance from a paltry $2.5 million grant from the US National Institute of Drug Abuse of the NIH.
[24] This program is based on Cohen's HPTN 052 research supporting Treatment as Prevention and aims to expand access to HAART among hard-to-reach and vulnerable populations in the Downtown East-Side area of Vancouver.
[23] Montaner is a proponent of harm reduction policy and played a minor role for his colleagues at the BC-CfE, was involved in founding and supporting the Insite Safe Injection facility in Vancouver's Downtown East-Side.
[25] Montaner has co-authored many studies on the effect of safe injection facilities on drug overdoses and deaths, HIV and Hepatitis C infections and the spread of other blood-borne pathogens.
[26][27][28] Montaner's current major research interests are harm reduction (including safe injection sites and needle exchange programs), treating hard-to-reach HIV-positive populations, and developing new antiretrovirals.
[2][5] He received a grant of $2.5 million over 5 years in 2008 from the National Institute on Drug Abuse to support his "Seek and Treat for Optimal Outcomes and Prevention in HIV & AIDS in IDU (STOP HIV/AIDS)" project.
[7] He also is working on improving the engagement and treatment of hard-to-reach or rural HIV positive populations as part of a $48 million grant from the Ministry of Health of the Province of British Columbia.
[6] Montaner started his career at a time where very little was known about HIV and how it was spread, and there was much resistance from some of the staff and medical community at St. Paul's Hospital about their developing reputation as a center for HIV/AIDS in the early 1990s.
Health Canada initially denied the appeal, but after public pressure from Montaner and other HIV activists, granted permission for the use of the drugs in a clinical trial.
[31] In 2009, 4 years after starting the clinical trial, Kerr's CD4+ count has significantly improved and his viral load has fallen, and he appears in general good health, indicating that the drugs are working.
[37] This followed after years of frustrated advocacy by Montaner who stated his belief in 2012 that the stigmas associated with the transmission routes of HIV are responsible for the Canadian government's hesitancy to embrace the strategy in an interview with the Globe and Mail.
[35] In an interview with Positive Live in the same year, he stated that "Canada has this amazing made-in-Canada strategy that has now been recognized by Science as the number one scientific breakthrough for 2011.