Pre-Exposure Prophylaxis (PrEP) as a form of HIV prevention

This paper was originally published in October, 2012. To ensure its accuracy, updates have been made as new data surrounding the efficacy of and access to PrEP emerge.

The AIDS Committee of Toronto (ACT) supports the introduction of innovative strategies that help to reduce the transmission of HIV, including Pre-Exposure Prophylaxis (PrEP).

ACT believes that PrEP should be a part of a comprehensive approach to HIV prevention that includes access to condoms and lubricants, risk reduction counselling, information provision, the scale-up of social and behavioural interventions, access to regular and voluntary HIV and STI testing, community development activities, as well as the development of other biomedical interventions such as mircobicides.

While PrEP is not licensed for use in Canada as an HIV prevention method, it is being prescribed "off label" for these purposes. ACT encourages the implementation of PrEP in Canada and welcomes further research to inform individuals, communities and health care providers regarding its use as an HIV prevention technique. ACT is concerned about the costs associated with accessing PrEP off-label in Canada and encourages its coverage under both private and public drug plans.


In July 2012, the US Food and Drug Administration (FDA) approved the licensing of the anti-HIV medication Truvada for PrEP, and have developed guidelines for PrEP eligibility and implementation1. Truvada’s safety and efficacy for PrEP were demonstrated in two large, randomized, double-blind, placebo-controlled clinical trials: The iPrEx trial evaluated Truvada in 2,499 HIV-negative gay men or transgender women who have sex with men with evidence of high risk behaviour for HIV infection, such as inconsistent or no condom use during sex with a partner of positive or unknown HIV status, a high number of sex partners, and exchange of sex for commodities. Results showed Truvada was effective in reducing the risk of HIV infection by 44 percent compared with placebo in this population. Efficacy was strongly correlated with drug adherence in this trial: in a sub-study that measured Truvada drug levels in participants, comparing those with drug measured in their blood (i.e. those that were adherent with their medications) to those with no drug measured in their blood (i.e. those that were non-adherent), the effectiveness of reducing the risk of HIV infection rose to 92 percent.

The Partners PrEP trial was conducted in 4,758 heterosexual couples where one partner was living with HIV and the other was not (serodiscordant couples). The trial evaluated the efficacy and safety of Truvada and Tenofovir versus placebo in preventing HIV infection in the uninfected male or female partner. Results showed Truvada reduced the risk of becoming infected by 75 percent compared with placebo.

As these large-scale trials continue to develop, the efficacy of PrEP, when taken daily, is being shown to reduce the transmission of HIV by over 90% and as high as 99%.

PrEP was also endorsed by the World Health Organization (WHO) for use among men who have sex with men that may be at higher risk for HIV infection in July 2014 2.

According to the FDA, “Truvada for PrEP is meant to be used as part of a comprehensive HIV prevention plan that includes the following:
• HIV risk reduction counselling
• consistent and correct use of condoms
• regular HIV testing (at least every three months)
• screening and treatment for sexually transmitted infections (STIs)."

Truvada will not prevent the transmission of other STIs including syphilis, gonorrhea and chlamydia. Some STIs increase the likelihood of HIV infection. Regular STI testing and treatment is therefore integral to the use of PrEP.

When used as PrEP, Truvada should be taken every day in people who are confirmed to be HIV negative. The FDA warns that when used as PrEP, Truvada must not be prescribed to patients whose HIV status is ‘unknown’ (ie. they have not been tested for HIV) or who are HIV-positive (as this could lead to the development of drug resistance as Truvada is always prescribed in combination with other anti-HIV medications for those who are HIV-positive). The FDA encourages physicians to test their patients who use PrEP for HIV at least every three months.

Truvada is not approved in Canada or other countries for use as PrEP; it is however, approved for HIV treatment and is therefore available with a prescription. Truvada manufacturer Gilead Sciences has yet to seek approval for Truvada as PrEP in Canada, Western Europe and Australia. In Canada, a month’s supply of Truvada (for HIV treatment) costs between $800 - $1,100 per month.

Concerns exists as to whether public and private drug plans in the US will cover the costs associated with Truvada as PrEP, thus reducing access to PrEP for those who might benefit the most from it.

ACT is dedicated to strengthening the health and well-being of the communities it serves and recognizes its role in communicating the benefits and limitations of emerging HIV prevention technologies. ACT is optimistic about the implementation of PrEP in Canada, but is concerned about the costs associated with accessing PrEP off-label in Canada. To that end, we encourage its coverage under both private and public drug plans, and support efforts to achieve such access.

1 Interim Guidance: Preexposure Prophylaxis for the Prevention of HIV Infection in Men Who Have Sex with Men:

2. WHO: People most at risk of HIV are not getting the health services they need