15 September 2015 

Inside an HIV prevention clinic—trying to transition from PEP to PrEP

People who have been exposed to HIV may prevent this virus from being established by taking post-exposure prophylaxis (PEP). This involves starting anti-HIV medicines within 72 hours of exposure and continuing to take these medicines every day for 28 consecutive days.

Continually resorting to PEP is not the best way to prevent HIV, so doctors and researchers do not expect PEP to be widely used or to have a major effect on the spread of HIV within a region or country for at least the following reasons, some of which have been documented in studies:

  • PEP is used reactively rather than proactively, and doctors and nurses cannot predict when exactly it may be needed.
  • People who use PEP may not take it every day, exactly as directed.
  • People who first seek PEP in a hospital emergency room (ER) may not keep appointments to receive future doses of medicines, counselling and HIV testing.
  • People who seek PEP are likely to be at high risk for future episodes where they can again become exposed to HIV.

The ideal way to help people who are at continuous risk for re-exposure to HIV would be through sexual health counselling that includes a discussion of HIV pre-exposure prophylaxis (PrEP).

PrEP generally involves the use of a fixed-dose combination of two anti-HIV medicines—tenofovir and FTC, in a single pill sold as Truvada—taken every day. Clinical trials have found that Truvada can be highly effective in preventing HIV transmission, particularly among men who have sex with men (MSM). Despite these promising results, widespread use of Truvada as PrEP has not occurred among MSM in high-income countries. Some of the reasons hindering the widespread use of Truvada as PrEP are explored in a previous CATIE News story.

A Toronto study

Researchers in Toronto have conducted an observational study to evaluate a program that assessed which patients using PEP would be good candidates for PrEP once their course of PEP was completed.

In evaluating the program, researchers found that there was very good agreement about who should get PrEP between the guidelines produced by the U.S. Centers for Disease Control and Prevention (CDC) and physician assessment of patients. The Toronto researchers stated that “combining PEP and PrEP services in a dedicated clinic” might be an ideal way to identify candidates for PrEP and to help increase the use of PrEP.

About the clinic

Before we delve into the study, we first provide some background about what takes place at the clinic.

The HIV Prevention Clinic at the Toronto General Hospital offers an array of services for people at risk for HIV. These services include at least the following:

  • safer-sex counselling
  • access to care providers in the following specialities: nursing, pharmacy, social work, psychiatry and infectious diseases
  • assessment for and prescription of PrEP

The clinic receives clients referred by the emergency departments of local hospitals as well as from family doctors and sexual health clinics in Toronto.

Before being referred to the clinic, ER patients receive what doctors call a “starter pack” that contains sufficient doses of PEP to tide them over until they can get an appointment at the clinic. The contents of the starter pack are usually as follows:

  • Truvada + raltegravir (Isentress)

Visiting the clinic

At a patient’s first visit to the clinic, staff members perform what they call a “comprehensive medical assessment” and ask detailed questions about “events surrounding the exposure [to HIV].” Doctors, nurses and other staff at the clinic take care to treat patients in a non-judgmental manner and make them feel welcome.

Once they have collected and assessed this information, doctors then estimate the patient’s risk of HIV infection. At this point, PEP is either stopped (if the risk for acquiring HIV was judged to be low) or continued for a total of 28 days if the risk was judged to be high.

Patients are also screened for the following:

  • pregnancy
  • hepatitis B virus
  • hepatitis C virus
  • other infections, including sexually transmitted infections (STIs)

Once screened, patients are given vaccines for certain STIs and other infections as necessary.

After the initial clinic visit, patients are seen again one or two weeks later so that doctors can assess their tolerance and adherence to PEP. Additional appointments are then offered at regular intervals over the next six months. At these visits, staff perform repeated screening for STIs, including HIV, and monitor the effectiveness of vaccines.

All patients who seek PEP are assessed to determine if they are candidates for PrEP. Clinic staff offer PrEP if patients are in the following situations:

  • in an ongoing relationship with an HIV-positive partner
  • using condoms infrequently with one or more partners of unknown HIV status
  • an MSM who has had an STI in the past six months
  • sharing equipment for injecting substances in the past six months
  • have been in an opioid substitution program (using methadone, buprenorphine or Suboxone) in the past six months

In transitioning patients from PEP to PrEP, doctors at the HIV Prevention Clinic conduct thorough screening and blood tests to confirm the following:

  • no signs or symptoms of acute HIV infection
  • a negative test for HIV antibodies
  • a negative test for HIV’s genetic material

Back to the study

Researchers reviewed data collected between January 2013 and September 2014. During that period, 125 participants sought PEP. However, for their analysis, researchers focused on 99 participants, as this was the number who attended at least two clinic appointments or disclosed sufficient information on their first visit so that they could be evaluated for future use of PrEP.

The average profile of participants was as follows:

  • age – 32 years
  • 84% men, 16% women
  • a majority of men were MSM
  • 66% were white (detailed ethno-racial data were not released)


Thirty-one participants fulfilled the criteria established by the CDC identifying them as suitable candidates for PrEP. According to the researchers, “there was very good agreement between CDC guideline recommendation and physician recommendation for PrEP candidacy.”

Using statistical analysis, the researchers found that the following factors were highly linked to a patient being a suitable candidate for PrEP:

  • having sexual vs. non-sexual exposure to HIV
  • being an MSM
  • having used PEP in the past

Cost issues and HIV prevention

Subsidized access to PrEP is not widely available across Canada, with the exception of Quebec. Outside of that province, people who have private drug plans may be able to get the cost of HIV medicines (when used to prevent infection) subsidized. However, in the present study, researchers found that people who were candidates for PrEP were less likely to have private drug insurance than people who were unlikely to need PrEP.

The cost of drugs used for preventing HIV can be expensive. For instance, one year’s supply of Truvada can cost about $13,000 per person. A one-month supply of PEP can cost between $1,000 and $2,000 per person, depending on the regimen used. Therefore, the costs of these medicines can be a significant barrier when attempting to access PrEP and PEP to prevent HIV transmission arising from consensual sex in many parts of Canada.

Given this background of expensive drugs, it should not be surprising that only 11 participants were able to initiate PrEP in the Toronto study.

Under one roof

Having an HIV prevention clinic that provides comprehensive care is likely the ideal way to serve a community of people at high risk for HIV. By concentrating services in one location, providers can offer care that prevents HIV and, through social workers and psychiatrists, begin to address the psychological drivers that place some people at high risk for HIV. In providing a nonjudgmental approach with patients, the clinic can help build a trusting relationship with patients and links with the larger community of people at high risk for HIV. Such trust and links are very helpful in encouraging safer behaviour and adherence to prescribed medicines such as PrEP and PEP.

Cost as a barrier

The clinic researchers have identified a major issue: The cost of medicines is an immense barrier to people’s ability to access PrEP. Until this issue is addressed, PrEP will not become a widely used tool to prevent the spread of HIV.

—Sean R. Hosein


Pre-exposure prophylaxis (PrEP) – CATIE fact sheet

Moving PrEP into practice: an update on research and implementationPrevention in Focus

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

Clinical practice guidelines for providing PrEP – U.S. Centers for Disease Control and Prevention (CDC)

U.S. researchers study steps needed to increase PrEP useCATIE News

High rate of mental health issues found among some PEP usersCATIE News


Siemieniuk RA, Sivachandran N, Murphy P, et al. Transitioning to HIV pre-exposure prophylaxis (PrEP) from non-occupational post-exposure prophylaxis (nPEP) in a comprehensive HIV prevention clinic: A prospective cohort study. AIDS Patient Care and STDS. 2015 Aug;29(8):431-6.