News Release

New HIV guidelines outline prevention strategies for high-risk populations

New Canadian guidelines recommend the use of new medications by HIV-negative people from high-risk populations both before and after exposure to the virus to prevent HIV infection

Peer-Reviewed Publication

St. Michael's Hospital

Dr. Darrell Tan, St. Michael's Hospital

image: Dr. Darrell Tan, lead author of the guidelines, is an infectious disease physician and scientist at St. Michael's Hospital in Toronto. view more 

Credit: Courtesy of St. Michael's Hospital

TORONTO, Nov. 27, 2017--New Canadian guidelines recommend the use of new medications by HIV-negative people from high-risk populations both before and after exposure to the virus to prevent HIV infection.

The guidelines, published online today in CMAJ, recommend both pre-exposure prohylaxis, or PrEP, the regular use of antiretroviral medications beginning before an exposure occurs, and non-occupational post-exposure prophylaxis, and nPEP, a course of antiretroviral medications after a sexual or drug use-related exposure to HIV, as highly effective strategies prevent new HIV infections.

These biomedical interventions should be used as part of a combination prevention strategy that also includes behavioural interventions, such as condoms and risk reduction counseling, according to the guidelines.

"There are new biomedical HIV prevention strategies that have been widely endorsed worldwide by organizations including the WHO, U.S. CDC and others," said Dr. Darrell Tan, an infectious disease physician and scientist at St. Michael's Hospital and lead author of the guidelines. "In particular, PrEP is a highly effective and safe Health Canada-approved method that involves taking a daily pill, which, if taken properly, can offer almost 100 per cent protection against new HIV infection."

The guidelines are particularly important in populations where HIV incidence in Canada remains disproportionately high, according to the authors.

Men who have sex with men are 131 times more likely to acquire HIV than other Canadian men, with fifty four per cent of all new HIV infections in Canada occurring in this population. Injection drug users are 59 times more likely than non-users to acquire HIV. People from countries with endemic HIV, as well as Indigenous people, are also both more likely than the general population to acquire HIV (6.4 times and 2.7 times more likely, respectively).

Economic analyses have shown that PrEP and nPEP, when used in high-risk populations, are also cost-effective HIV prevention strategies, according to the authors.

"To date, the cost of these medications has restricted the feasibility and acceptability of these strategies," said Dr. Tan. "However, the recent introduction of generic versions of antiretroviral medications, as well as increasing availability of public drug coverage for PrEP in Canada may have a substantial effect on their uptake."

The guidelines are generally consistent with international guidelines from the United Kingdom, the United States and Australia, according to the authors.

"Previous studies in these countries have shown that widespread use of PrEP led to dramatic reduction in new HIV diagnoses," said Dr. Tan. "We hope that these guidelines can provide clinicians with the resources they need to incorporate biomedical interventions into their care plans, and ultimately help Canada work towards eliminating new HIV infections."


This study received funding from the Canadian Institutes of Health Research with support from the CIHR Canadian HIV Trials Network.

About St. Michael's Hospital

St. Michael's Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 29 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital's recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.

About the CIHR Canadian HIV Trials Network

The CIHR Canadian HIV Trials Network (CTN) is funded by the Canadian Institutes of Health Research (CIHR) and sponsored by the University of British Columbia and St. Paul's Hospital (Providence Health Care). The CTN is a partnership of clinical investigators, physicians, nurses, people living with HIV, pharmaceutical manufacturers and others committed to developing treatments, vaccines and a cure for HIV and related conditions through the conduct of scientifically sound and ethical clinical trials. The CTN is committed to the pursuits of scientific excellence and ethical integrity in all undertakings. We are also dedicated to working in partnership with the international and national pharmaceutical industry, people living with HIV, researchers and physicians.

Media contacts

For more information, or to arrange an interview with one of the authors, please contact:

Kelly O'Brien
Communications Adviser - Media

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