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Initiating combination anti-HIV therapy (ART) can greatly reduce the amount of HIV in the blood (viral load). Over time, as the viral load continues to fall, in the majority of people it reaches a very low level that cannot be accurately assessed using routine laboratory tests. Such low viral load levels are commonly called “undetectable.”

Continuing to take ART every day helps to maintain an undetectable viral load. By suppressing HIV, ART allows the immune system to partially repair itself. Over the long term, all of these changes generally result in improved health. The benefits of ART are so significant that researchers increasingly expect that many ART users will have near-normal life expectancy.

There is another advantage that comes with a continuously suppressed viral load—the inability of HIV to be transmitted. Studies have found that people who initiate ART and who achieve and maintain an undetectable viral load do not pass on HIV to their sexual partners. Furthermore, the U.S. Centers for Disease Control and Prevention (CDC) recently issued a statement confirming this.

These twin benefits of ongoing ART—treating and preventing the spread of HIV—are so tremendous that the Joint United Nations Program on AIDS (UNAIDS) has called for regions and countries to achieve the following goals by 2020:

  • 90% of people with HIV are aware of their infection status
  • 90% of people diagnosed with HIV are taking ART
  • 90% of people taking ART have an undetectable viral load

In order to reach these 90-90-90 targets, more opportunities for HIV testing need to become available, along with supportive counselling and swift referral to care where an offer of ART can be made.

In British Columbia

In 2010 the B.C. Ministry of Health launched a pilot program called “Seek and Treat for the Optimal Prevention of HIV/AIDS” (STOP AIDS) in two health regions. The pilot program ran from 2011 to 2013 and focused on at least the following areas:

  • HIV testing
  • ART initiation
  • retaining people in care and on ART

Researchers at the BC Centre for Excellence in HIV/AIDS developed a computer model to assess the economic impact of the interventions associated with the STOP AIDS project. They found that, overall, the interventions associated with HIV testing and ART initiation were very cost-effective. That is, although these interventions cost money, over the long term their impact on health resulted in the Ministry of Health saving money because fewer people became infected with HIV.

In an era of enforced austerity, assessing HIV prevention initiatives is important, as it can help guide future efforts at improving such initiatives and can help inform decision-making about deploying scarce resources.

Study details

As part of the STOP AIDS project, the following interventions were deployed:

  • HIV testing was offered in different settings such as hospital emergency departments, health clinics and so on
  • ART initiation was offered for people who tested HIV positive
  • attempts were made to help some people who stopped taking ART to re-engage with their care and treatment

Although interventions were made in two health regions—Vancouver Coastal Health and Northern B.C.—the researchers used data collected from the Vancouver Coastal Health region for their analysis. They focused on this region because it has 25% of the province’s population and is home to 50% of its HIV-positive people.

In performing their analysis, the researchers took into account many factors, including costs associated with at least the following:

  • HIV testing
  • ART and pharmacy dispensing fees
  • prescription drugs other than ART
  • medical care unrelated to HIV
  • hospital-based care
  • family practice care
  • lab tests
  • staffing and facilities costs

To follow the trajectory of the epidemic in that health region, the researchers also factored in new HIV infections and related deaths into their model.

For the purposes of comparison, researchers assessed similar factors for the Vancouver Coastal Health region between 2006 and 2010—the period before the STOP AIDS project was implemented.

The researchers' basic computer model had been previously used for estimating “the health benefits and costs of expanded HIV screening and treatment in the U.S. and in B.C.” For the present study, researchers adjusted the model to help it provide accurate estimates for trends in the Vancouver Coastal Health region.


According to the researchers, if the interventions of the STOP AIDS pilot project were sustained beyond 2013, the following benefits would occur:

  • nearly 600 HIV infections would be prevented
  • 217 deaths (among HIV-positive people) would be prevented

If the interventions in the pilot project were discontinued, only 111 HIV infections and 50 deaths would be prevented.

The researchers found that if the pilot project interventions were extended between five and 25 years into the future, they would be “very cost-effective.” That is, the money invested in preventing HIV infections would be recovered and less money would need to be spent because of future savings in healthcare costs (because HIV infections and complications would have been prevented).

The researchers found that HIV testing offered in hospital emergency departments is highly cost-effective.

According to the researchers, the least cost-effective intervention involved getting those who quit ART to re-engage with care and treatment. The researchers acknowledged that they could only “crudely” assess this intervention. Nonetheless, the finding by the B.C. team could serve as the impetus to improve this intervention and make it cost-effective.

However, the researchers also point to the future, when long-acting ART delivered by injection could one day become an option for some people who have difficulty taking medicine daily.


The researchers stated that they “have not provided an exhaustive account and evaluations of all interventions executed as part of the STOP AIDS pilot project, but rather a selection of those with sufficient information to provide reasonable estimates of scale of delivery and effectiveness.”

Also, this was not a randomized study. Such a study would have been enormously expensive, complex and time consuming. However, the researchers performed statistical analyses to confirm the validity of their findings. As a result, they were able to accurately model the HIV epidemic.

The study was based on data captured from the Vancouver Coastal Health region and its findings may not be applicable to other regions in B.C. or Canada that have different factors affecting the spread of HIV. However, since the success of the pilot project, other health regions in B.C. have adapted elements of the STOP AIDS project to bridge their gaps in HIV testing, care and treatment.

Investing in public health and reducing the spread of HIV

Assessing the economic impact of health interventions is particularly necessary in an era of enforced austerity when difficult decisions need to be made about deploying scarce resources. The B.C. study also shows that there is a cost—in money and in lives—that society incurs if we do not invest in strengthening public health, in this case, to greatly slow the spread of HIV.

In parallel with the work by the BC Centre for Excellence in HIV/AIDS, a research team at Harvard University in Boston has done an analysis of the impact that investing in HIV prevention initiatives (including ART initiation) would have on the HIV epidemic in the U.S. as that country attempts to attain the UNAIDS 90-90-90 targets. The researchers found that substantial declines in HIV infections (280,000 fewer infections) and deaths (45,000 fewer deaths) could occur over the next 20 years if the right investments are made in the United States.


BC Centre for Excellence in HIV/AIDS

The Vancouver STOP Project ­– Programming Connection

90–90–90 - An ambitious treatment target to help end the AIDS epidemic – UNAIDS

The HIV treatment cascade – patching the leaks to improve HIV preventionPrevention in Focus

The Engagement CascadeThe Positive Side

The routine offer of HIV testing in primary care settings: A review of the evidencePrevention in Focus

The HIV testing process – CATIE fact sheet

HIV testing technologies – CATIE fact sheet

—Sean R. Hosein


  1. Nosyk B, Min JE, Krebs E, et al. The cost-effectiveness of HIV testing and treatment engagement initiatives in British Columbia, Canada: 2011-2013. Clinical Infectious Diseases. 2017; in press.
  2. Borre ED, Hyle EP, Paltiel AD, et al. The clinical and economic impact of attaining National HIV/AIDS Strategy treatment targets in the United States. Journal of Infectious Diseases. 2017; in press.
  3. Cohen MS, Chen YQ, McCauley M, et al. Antiretroviral therapy for the prevention of HIV-1 transmission. New England Journal of Medicine. 2016;375:830–9. Available from: http://www.nejm.org/doi/pdf/10.1056/NEJMoa1600693
  4. Rodger AJ, Cambiano V, Bruun T, et al. Sexual activity without condoms and risk of HIV transmission in serodifferent couples when the HIV-positive partner is using suppressive antiretroviral therapy. Journal of the American Medical Association. 2016;316(2):171–81. Available from: http://jama.jamanetwork.com/article.aspx?articleid=2533066