HIV in Canada: A primer for service providers

 

Post-exposure prophylaxis (PEP)

Key Points

  • Post-exposure prophylaxis (PEP) is the use of antiretroviral drugs after an exposure to HIV, to reduce the risk of HIV transmission.
  • PEP works by helping to prevent replication of HIV once it has made its way into the body.
  • PEP can reduce the risk of HIV transmission by over 80% when used consistently and correctly.
  • PEP is meant for emergencies only.

Post-exposure prophylaxis (PEP) is the use of antiretroviral drugs after an actual or suspected exposure to HIV to reduce the risk of HIV transmission. It should be started as soon as possible after a potential HIV exposure but definitely within 72 hours. A combination of three antiretroviral drugs is generally prescribed for PEP use. These medications must be taken every day for four weeks.

PEP works in an HIV-negative person after HIV has entered the body. If this happens, the medications in PEP can prevent the virus from multiplying and spreading throughout the body and causing a permanent infection.

Research has found that PEP can reduce the risk of HIV infection by over 80%. In those studies PEP was not always used consistently and correctly, so this number is likely much higher when PEP is used as prescribed. Factors that can limit the effectiveness of PEP include: low adherence to the full four-week course of pills, later PEP initiation, and continued exposures to HIV while taking PEP (PEP is only meant to reduce the risk from a single exposure).

PEP is generally well tolerated and associated with minimal side effects. Other potential risks of PEP include drug toxicity, interactions with other medications, and the development of drug-resistant strains of HIV (if infection occurs while the person is taking PEP). A person who wants to use PEP will have their HIV risk assessed, because PEP is only meant to be used after a potential high-risk exposure. They will also be tested for HIV to confirm that they are HIV negative.

PEP is meant for emergencies only and is not intended for people with ongoing exposures to HIV. People who engage in high-risk behaviours on a regular basis, or who find themselves using PEP frequently, should consider using pre-exposure prophylaxis (PrEP) to prevent HIV instead.

Resources

Post-Exposure Prophylaxis for Prevention (PEP)

Post-exposure Prophylaxis (PEP) – CATIE fact sheet

Canadian guideline on HIV pre-exposure prophylaxis and nonoccupational postexposure prophylaxis

HIV Post-Exposure Prophylaxis (PEP) Guidelines – British Columbia Centre for Excellence in HIV/AIDS

Alberta Guidelines for Non-Occupational, Occupational and Mandatory Testing and Disclosure Act Post-Exposure Management and Prophylaxis: HIV, Hepatitis B, Hepatitis C and Sexually Transmitted Infections –  Alberta Health Services

Guide pour la prophylaxie et le suivi après une exposition au VIH, au VHB et au VHC – 2017, Ministry of Health and Social Services of Quebec

Sources

  1. Cardo DM, Culver DH, Ciesielski CA, et al. A case-control study of HIV seroconversion in health care workers after percutaneous exposure. Centers for Disease Control and Prevention Needlestick Surveillance Group. New England Journal of Medicine. 1997 Nov 20;337(21):1485–1490.
  2. Schechter M, do Lago RF, Mendelsohn AB, et al. Behavioral impact, acceptability, and HIV incidence among homosexual men with access to postexposure chemoprophylaxis for HIV. Journal of Acquired Immune Deficiency Syndromes. 2004 Apr 15;35(5):519–525.
  3. Barber TJ, Benn PD. Postexposure prophylaxis for HIV following sexual exposure. Current Opinion in HIV and AIDS. 2010 Jul;5(4):322–326.
  4. Poynten IM, Jin F, Mao L, et al. Nonoccupational postexposure prophylaxis, subsequent risk behaviour and HIV incidence in a cohort of Australian homosexual men. AIDS London England. 2009 Jun 1;23(9):1119–1126.
  5. Heuker J, Sonder GJB, Stolte I, et al. High HIV incidence among MSM prescribed postexposure prophylaxis, 2000-2009: indications for ongoing sexual risk behaviour. AIDS London England. 2012 Feb 20;26(4):505–512.
  6. Roland ME, Neilands TB, Krone MR, et al. A randomized noninferiority trial of standard versus enhanced risk reduction and adherence counseling for individuals receiving post-exposure prophylaxis following sexual exposures to HIV. Clinical Infectious Diseases. 2011 Jul;53(1):76–83.
  7. Dodds C, Hammond G, Keogh P, et al. PEP talk: awareness of, and access to post-exposure prophylaxis among gay & bisexual men in the UK. London: Sigma Research; 2006 Nov. Available from: www.sigmaresearch.org.uk/downloads/report06d.pdf