The concept that antiretroviral therapy (ART) can impact HIV transmission has been under consideration since ART first emerged in the 80’s. While it has been clear that biologically ART can decrease HIV transmission, there has been a longstanding concern this effect could be overwhelmed by increased risk behaviors, commonly referred as behavioral disinhibition, risk overcompensation or therapeutic optimism.
However, shortly after the roll out of highly active antiretroviral therapy (HAART) in 1996, ecological data from Taiwan and British Columbia suggested that HIV new diagnoses had decreased in an unexpected fashion. Most intriguingly, in British Columbia, the effect of HAART on HIV new cases was apparent despite a steady rise in syphilis rate. At the same time, it became clear HAART had the potential to eliminate vertical transmission of HIV. Taken together, these data suggested that HAART could be much more effective in reducing HIV transmission at the population level than it had been previously suspected.
These observations fueled the interest of the BC Centre for Excellence in HIV/AIDS (BC-CfE) to further explore the potential of HIV treatment as prevention. The latter was addressed using demographic and mathematical models, which surprisingly suggested that maximal coverage with HAART could lead to the near elimination of HIV transmission. These results were both published in the Lancet in 2006 and presented at the International AIDS Conference in Toronto.
In brief, HAART rapidly and effectively decreases HIV levels to undetectable in blood and sexual fluids in the vast majority of treated patients. Among those infected, HAART induced sustained HIV undetectability allows for immune reconstitution, therefore preventing the emergence of AIDS-related diseases and premature death. At the prevention level, HAART induced sustained HIV undetectability markedly reduces the likelihood of HIV transmission.
B.C. has experienced a marked decrease in HIV/AIDS morbidity and mortality since the implementation of HAART in 1996. This has been associated with a nearly 60% decrease in new HIV diagnoses, to the current level of 301 cases diagnosed in 2010. More recently, HIV treatment as prevention initiatives have been initiated in a number of jurisdictions around the world, including San Francisco, New York City, Washington, D.C. and China.
Check out Dr. Julio Montaner's presentation on Treatment as Prevention from TEDxSFU 2011:
The BC-CfE is aiming the Treatment as Prevention social media campaign at the province’s young adults through an interactive website, where visitors can learn about how they can help to stop the spread of HIV/AIDS in British Columbia. Visitors are encouraged to pledge to take the HIV test and share their pledge with friends through Facebook and Twitter. The campaign calls for people to ‘Share the Pledge, Take the Test.’