Post-exposure prophylaxis to prevent HIV infection

Fact sheet - 1 December 2014

Key facts

  • Globally, there were an estimated 35 million people living with HIV, of whom 13 million were on antiretroviral treatment (ART) at the end of 2013.
  • People can be accidentally exposed to HIV though healthcare work or due to exposures outside healthcare setting, for example, through unprotected sex or sexual assault.
  • Antiretrovirals (ARVs) have been used to prevent infection in case of accidental exposures for many years. This intervention is called post-exposure prophylaxis (PEP) and involves taking a 28-day course of ARVs.
  • PEP should be offered, and initiated as early as possible, for all individuals with an exposure that has the potential for HIV transmission, and ideally within 72 hours.
  • If started soon after exposure, PEP can reduce the risk of HIV infection by over 80%. Adherence to a full 28-day course of ARVs is critical to the effectiveness of the intervention.
  • Recent evidence shows PEP uptake has been insufficient: only 57% of the people who initiated PEP have completed the full course and rates were even lower at 40% for victims of sexual assault.

Why guidelines are needed

For many people that are accidentally exposed to HIV, PEP provides a single opportunity to prevent HIV after exposure. Such accidental exposures may be among health care workers who had needle stick injuries or among adults and children who survived sexual violence.

Access to timely PEP remains challenging in many settings in particular for non-health worker exposures(1). Recent studies highlight the need to simplify approaches and improve the use of HIV PEP. Reported issues include, missed opportunities to provide PEP following sexual exposure in the United Kingdom (3), lack of PEP protocols and limited compliance to guidance in China (4), Nigeria (5) and UK (6), limited access to PEP by female sex workers in Kenya (7) and health workers in Uganda (8), and structural stigma that reduces PEP uptake among men who have sex with men in the United States of America (9)

WHO response

  • In December 2014, WHO releases an update which includes a new set of recommendations for PEP (10). This update is the second supplement of the WHO consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection, released in June 2013.
  • New WHO guidelines aim to simplify PEP prescribing and improve adherence and completion rates by recommending better tolerated drugs. Recommendations for PEP are also aligned with recommendations for ART as a way to simplify procurement and improve access.
  • For the first time, the PEP recommendations cover all types of exposures, and in all population groups, including adults, adolescents and children. Traditionally, separate WHO and national guidelines have been developed for PEP according to exposure type (occupational or non-occupational) and populations (adults or children).

Key recommendations

  • The recommended PEP regimens are:
    • For adults: Tenofovir combined with either lamivudine (3TC) or emtricitabine (FTC) as preferred backbone drugs and these are also the preferred drugs for treating HIV. The recommended third drug is ritonavir-boosted lopinavir (LPV/r), which is also recommended by WHO as a preferred drug for HIV treatment.
    • For children: Zidovidune (AZT) and lamivudine (3TC) backbone drugs for children aged 10 or below, with ritonavir-boosted lopinavir (LPV/r) recommended as the third drug choice. This is also in alignment with preferred drugs for treating HIV in children.
  • Recommendations for simplifying prescribing approaches and supporting adherence include:
    • Prescribing: To improve uptake and completion of PEP, WHO recommends providing the full 28-day course at first visit, rather than requiring patients to return multiple times for prescriptions.
    • Adherence support: To improve adherence and completion rates, WHO suggests programmes offer enhanced adherence counselling.


  • Anon. Guidelines on Post Exposure Prophylaxis for HIV. Recommendations for a Public Health Approach. World Health Organization, Geneva, 2014.
  • Patel P, Borkowf CB, Brooks JT, Lasry A, Lansky A, Mermin J. Estimating per-act HIV transmission risk: a systematic review. Aids 2014; 28(10): 1509-19.
  • Arkell P, Abouyannis M, Manavi K. Can emergency departments fulfil BASHH recommendations for 24-hour access to HIV postexposure prophylaxis following sexual exposure? International journal of STD & AIDS 2012; 23(1): 75-6.
  • Lin C, Li L, Wu Z, Wu S, Jia M. Occupational exposure to HIV among health care providers: a qualitative study in Yunnan, China. Journal of the International Association of Physicians in AIDS Care 2008; 7(1): 35-41.
  • Agaba PA, Agaba EI, Ocheke AN, Daniyam CA, Akanbi MO, Okeke EN. Awareness and knowledge of human immunodeficiency virus post exposure prophylaxis among Nigerian Family Physicians. Nigerian medical journal : journal of the Nigeria Medical Association 2012; 53(3): 155-60.
  • Rutland E, Sundaram S, Mani R. The awareness of postexposure prophylaxis for HIV infection following sexual exposure in emergency departments in a regional HIV network. International journal of STD & AIDS 2010; 21(9): 636-7.
  • Izulla P, McKinnon LR, Munyao J, et al. HIV postexposure prophylaxis in an urban population of female sex workers in Nairobi, Kenya. Journal of acquired immune deficiency syndromes 2013; 62(2): 220-5.
  • Kumakech E, Achora S, Berggren V, Bajunirwe F. Occupational exposure to HIV: a conflict situation for health workers. International nursing review 2011; 58(4): 454-62.
  • Oldenburg C, Perez-Brumer A, Hatzenbuehler M, et al. Structural Stigma Affects Access to Pre- and Post-exposure Prophylaxis and HIV Risk among Men Who Have Sex with Men (MSM) in the United States. AIDS research and human retroviruses 2014; 30 Suppl 1: A22-3.
  • Ford N, Irvine C, Shubber Z, et al. Adherence to HIV postexposure prophylaxis: a systematic review and meta-analysis. AIDS 2014. Published ahead of print.