Pre-exposure prophylaxis, or PrEP, is an exciting new HIV prevention strategy that involves the ongoing use of anti-HIV drugs by an HIV-negative person in order to reduce their risk of becoming infected with HIV. Many types of PrEP are currently being researched, but to date only one type has been found effective in multiple placebo-controlled clinical trials and approved by the Food and Drug Administration (FDA) in the United States. This form of PrEP involves taking a daily oral pill called Truvada, starting before a potential exposure to HIV and continuing afterwards. Truvada is a single pill that contains two anti-HIV drugs (tenofovir and emtricitabine). Research suggests that PrEP can reduce the risk of HIV infection by over 90% if taken every day.

Moving PrEP Into Practice

In addition to regulatory approval by the FDA, several other actions have been taken to move PrEP into practice in the United States. For example, the Centers for Disease Control and Prevention (CDC) have released comprehensive clinical guidelines recommending that healthcare providers offer PrEP as a potential prevention option to sexually active men who have sex with men (MSM), heterosexually active men and women, and injection drug users at "substantial" risk of HIV infection. Along with the guidelines, the CDC released a providers' supplement with additional tools for clinicians to use when prescribing PrEP.

In Canada, Truvada has not been approved for use as PrEP by Canada's regulatory agency (Health Canada) and only Quebec has developed guidelines for healthcare providers. Although Truvada is currently approved for only the treatment of HIV in Canada, some healthcare providers are choosing to prescribe Truvada for use as PrEP. The prescription of an approved drug for an unapproved use is known as an "off-label" prescription, and it is not prohibited.

Exploring the Uptake of PrEP

In general, prescriptions for PrEP can be obtained by people at risk of HIV infection in Canada and the United States from one of the following two sources:

  • a healthcare provider (such as a family physician or infectious disease doctor)
  • a PrEP demonstration project

PrEP demonstration projects involve the coordinated provision of Truvada to a small number of eligible candidates. The main purpose of these projects is to answer questions about how to implement this new strategy in a safe and effective way outside of the setting of a placebo-controlled clinical trial. There are several PrEP demonstration projects ongoing in different parts of the world, most of which are in the United States. In Canada, one project is ongoing in Montreal and another is planned for Toronto.

Recently, two studies were published describing the uptake of PrEP in the United States, both within and outside demonstration projects. Their results have provided interesting and important insight into the use and delivery of PrEP and are described below.

Early Experiences From Demonstration Projects in San Francisco

There are three demonstration projects ongoing in San Francisco, a city heavily impacted by HIV. Each project has integrated the delivery of PrEP into a different clinical setting: a municipal sexually transmitted infection clinic (San Francisco City Clinic), a private health maintenance organization (Kaiser Permanente Health Plan) and an HIV-specific reproductive health program (Bay Area Perinatal AIDS Center).

San Francisco City Clinic

San Francisco's municipal sexually transmitted infections (STIs) clinic serves approximately 12,000 people annually (38% are MSM and 1% are trans people). The clinic offers a range of services including testing and treatment for STIs and HIV, HIV post-exposure prophylaxis (PEP), family planning and emergency contraception. The rate of HIV infection among the MSM patients is high.

In October 2012, the clinic began offering PrEP to some of the MSM and transgender women attending the clinic. Between October 2012 and September 2013, 571 people were assessed for PrEP eligibility; 531 (93%) were eligible and offered PrEP and of those 261 (49%) decided to start PrEP. People with prior awareness of PrEP and higher risk behaviours were more likely to start taking PrEP once offered. The most common reasons people cited for not wanting to start PrEP included not having enough time to participate in the study (28%), being concerned about side effects (25%) and having the perception that they were not at risk for HIV (8%).

Of note, 15 of the people who started PrEP reported feeling stigmatized by others because they were taking it. This stigma originated from peers and healthcare providers.

Kaiser Permanente Health Plan

This private health organization provides medical services to over 185,000 people in San Francisco who are covered by a number of different insurance plans, including employer-based programs and a health access program for low-income individuals. The organization provides HIV-related services through its HIV Care and Prevention Program.

In May 2012, healthcare providers at the organization were encouraged to refer patients who were interested in PrEP to coordinators of the HIV Care and Prevention Program. These coordinators are nurses and pharmacists. Once referred, patients were assessed for eligibility and offered PrEP if eligible.

Between May 2012 and September 2013, 123 men and women were referred to the HIV program for PrEP; 118 (96%) were offered PrEP; and of those 70 (59%) started PrEP. The most common reasons that people cited for not starting PrEP once offered included deciding to take PEP instead of PrEP (47%) and having an underlying medical condition (11%). Of those who started, 24% discontinued PrEP for a variety of reasons.

Bay Area Perinatal AIDS Center

The Perinatal AIDS Center provides preconception management and prenatal care to HIV-positive women and HIV-negative women with HIV-positive male partners. Each year, approximately 10 to 15 HIV-positive pregnant women attend the center and eight to 10 women are provided preconception counselling.

In 2010, the center began offering PrEP to HIV-negative pregnant women who were having condomless sex with their HIV-positive partners. In 2012, the center also began offering PrEP to HIV-negative women who were trying to become pregnant.

Between January 2010 and September 2013, 15 women were assessed for PrEP eligibility; 11 (73%) were offered PrEP and of those seven (64%) initiated PrEP. The main reasons that women cited for not starting PrEP were lack of insurance coverage, perception of low risk, and concerns about side effects and toxicities (for themselves and their babies).

Use of PrEP Outside of Demonstration Projects

Gilead Sciences, the pharmaceutical company that manufactures Truvada, recently conducted a national study in the United States exploring the uptake of PrEP outside of demonstration projects. This study looked at prescriptions from about half (55%) of the retail pharmacies in the United States. The purpose of the study was to understand how many people are using PrEP and describe the characteristics of PrEP users and prescribers.

A total of 2,319 different individuals were found to have started PrEP between January 2012 and September 2013. Below are some characteristics of the PrEP users:

  • 49% were women.
  • The average age was 38 years, and male users tended to be a bit older than female users (average age 40 years vs. 37 years).
  • 12% were under 25 years, and this percentage was higher for females than males (17% vs. 8%).

PrEP was prescribed by a variety of healthcare providers, such as these:

  • family doctors or internal medicine specialists (34%)
  • infectious disease specialists (11%)
  • non-physician prescribers, including nurse practitioners and physician assistants (18%)

Among women who started PrEP, 49% were prescribed Truvada by a nurse practitioner and 43% received it from an infectious disease specialist.

Compared with people living with HIV in the United States, PrEP users were more likely to be women, younger, and treated by a physician who was not an infectious disease specialist.

Moving Forward With PrEP

These American studies demonstrate that people are interested in using PrEP and some healthcare providers are willing to prescribe it. Indeed, those leading the demonstration projects concluded that "interest in PrEP is high in San Francisco, particularly among men who have sex with men attending the [STI] clinic, and it is feasible to incorporate PrEP into busy clinical settings."

Despite this interest in PrEP and the demonstrated feasibility of this new strategy, PrEP use is generally low. The CDC estimates that approximately 500,000 people in the United States may benefit from PrEP but fewer than 10,000 are currently using it. A more pronounced disparity likely exists in Canada, particularly as Health Canada has not approved Truvada for use as PrEP, only one province has developed guidelines, and only two provinces have a planned or ongoing demonstration project. A recent survey of over 400 MSM at a busy sexual health clinic in downtown Toronto found that only 27% of men were aware of PrEP and none had used it.

Moving forward, addressing barriers to PrEP use will be important to ensure that those who may benefit from this strategy -- and who want to use it -- are able to access it. Priority next steps for implementation were identified by those leading the demonstration projects in San Francisco. These included "increasing PrEP knowledge; expanding PrEP access; combatting PrEP stigma; and optimizing interventions to promote PrEP uptake and adherence while reinforcing risk reduction strategies." Hopefully these next steps will be considered in Canada.


Clinical practice guidelines for providing PrEP -- CDC

Clinical providers' supplement for providing PrEP -- CDC

Interim guidance on providing HIV PrEP -- Quebec Ministry of Health (French only)

Pre-exposure prophylaxis (PrEP) -- CATIE Fact Sheet

Moving PrEP into practice: an update on research and implementation -- Prevention in Focus

Two North American surveys engage doctors about their attitudes towards PrEP -- CATIE News


  1. Liu A, Cohen S, Follansbee S, et al. Early experiences implementing pre exposure prophylaxis (PrEP) for HIV prevention in San Francisco. PLoS Medicine. 2014 Mar;11(3):e1001613.
  2. Mera R, Ng L, Magnuson D, et al. Characteristics of Truvada for pre-exposure prophylaxis users in the US (January 2012 - September 2013. HIV Drug Therapy in the Americas, Rio de Janiero, Brazil, May 8-10, 2014. Poster P28.
  3. Kain T, Fowler S, Grennan T, et al. Low perceptions of HIV risk among Toronto MSM seeking anonymous HIV testing: objective and subjective assessments of PrEP eligibility. In Poster Abstracts of Controlling the Epidemic with Antiretrovirals, London, UK, September 22-24, 2013. Abstract 22.