Does post exposure prophylaxis work?

Post-exposure prophylaxis (PEP) and pre-exposure prophylaxis (PrEP) are antiretroviral drug treatments which had been in both animal and human trials to see their effectiveness as treatments for HIV prevention.

Post-exposure prophylaxis (PEP)

There are no conclusive evidences which prove that they are 100 percent effective but the majority of research outcomes have pointed that they might play a pivotal role in reducing HIV transmission if tackled immediately before or after exposure, in occupational (healthcare workers)  and non-occupational settings (survivals of rape). For the common question that is thrown regarding question – Can PEP stop me getting HIV – what the NHS prefers as a response is “It’s possible, but it doesn’t always work.” It is for the reasons that so many factors would dictate the efficiency of this treatment. To start with, as per the article by the International HIV and AIDS charity, Avert, “In order for post-exposure prophylaxis to have a chance of working the medication needs to be taken as soon as possible, and definitely within 72 hours of exposure to HIV. Left any longer and it is thought that the effectiveness of the treatment is severely diminished.” If one  develops HIV, it can’t be cured. Hence, it would be a wise tactic to think of relying on PEP to prevent HIV as it doesn’t always work and the best preventive approach would be endorsing safe sex.

PEP has been available to health workers as an important aspect of safety in the workplace and has now extended to anybody who believes they have been exposed to HIV, hence rigorous treatments with adverse side-effects. They are similar treatments as the one who is normally confirmed as HIV patient would take. But as it is not guaranteed to work, post-exposure prophylaxis should only be used as a very last resort.

Debate about PEP administration

When a new yet expensive treatment is tabled, especially in welfare states like UK where basic healthcare is available for free for its citizens, the question of who should receive PEP has proved to be quite controversial. Several cost-benefit analyses have revealed that providing PEP to all non-occupational exposures is not an economically efficient use of limited HIV treatment resources, occupational settings prioritised for its administration with less fuss, particularly in the third world countries where the spread of HIV is frightening.

The crux of the matter emanates from the fear that health resources would be depleted if available for all who do not share the responsibilities and who should be prioritised. PEP appears to be cost-effective only when the patient has engaged in unprotected receptive anal intercourse or when the patient knows the HIV status of the partner. However, the demand for PEP does not always reflect cost-effectiveness.

According to the charity, Avert, “A ten year review of non-occupational PEP requests recorded at a Swiss clinic found an 850 percent increase in the number of people requesting PEP in the ten-year period and 58 percent of requests were for heterosexual exposure.” 

Others follow the slippery slope argument believing that the increasing availability of PEP will lead to behavioural changes. The theory is that if PEP is readily available people will be less likely to use condoms or will be less cautious, knowing that there is a potential back up.


Whom to contact

The provision of PEP is available in your nearest sexual health (GUM) clinic or A&E department. You’ll be asked some questions, for example:

  • who you had sex with, to assess your risk of exposure to HIV, and
  • whether you had oral, vaginal or anal sex.

According to the rules of PEP practice in NHS, the person in need of this treatment will be asked to take an HIV test before proceeding to treatment, to check whether he/she already have HIV. If the person concerned doesn’t agree to an HIV test, he/she won’t be given PEP.

Pre-exposure prophylaxis (PrEP)

According to Avert, “PrEP refers to a form of treatment that can be taken before exposure to a disease in an attempt to prevent infection, but with limited side-effects. In respect to HIV, PrEP consists of antiretroviral drugs to be taken before potential HIV exposure in order to reduce the risk of HIV infection.” PrEP research and practice is in its infant stage and has not been found, during its trials, to be of higher efficacy except for homosexual community at a higher risk.

“No single HIV prevention strategy is going to be effective for everyone… and it is important to note that the new findings pertain only to the effectiveness of PrEP among men who have sex with men and cannot at this point be extrapolated to other populations. Therefore, we must continue to conduct PrEP research among other study populations, such as women and heterosexual men, to provide a comprehensive picture of its potential utility as an HIV prevention tool.” Antony S. fauci, M.D., Director of the National Institute of Allergy and Infectious Diseases

This cutting-edge method has recently been trailed as a method to cut HIV transmission from mother to baby, Pre-exposure Prophylaxis for Conception (PrEP-C), by Doctors from Brighton & Sussex University Hospitals NHS Trust and the Heart of England NHS Foundation Trust in Birmingham. PrEP provides the anti-retroviral drugs usually used to treat HIV to the negative partner, in an effort to reduce the likelihood of sexual transmission of the infection between partners. But PrEP remains a method requiring further research before it can be widely adopted. The findings of this approach could be summed up using Dr Gilleece’s words as: “As far as we are aware, this is the first UK data on successful PrEP-C, undertaken in two dedicated HIV preconception clinics. It must be emphasised that using PreP-C is only a very small part of the very thorough process of assisting HIV discordant couples to conceive, and it should only be considered as part of an overall risk reduction strategy . The desire to have children is so strong that some couples have taken  risks in order to conceive – especially if they can’t afford to pay  for sperm washing. We’re aware of that problem, and so we’re trying to reduce the risk of transmission to as low a level as possible for them.”

Ethical debate on PrEP

With human trials of PrEP there are ethical issues both with using a placebo and withholding a potentially effective treatment.

According to Singh, J.A. & Mills, E.J., in their study ‘The Abandoned Trials of Pre-Exposure Prophylaxis for HIV: What went wrong?‘, “research trials in Cambodia, Cameroon and Nigeria were cancelled due to ethical concerns. Most notably the study of 960 female commercial sex workers in Cambodia was cancelled after a highly publicised demonstration at the XV International AIDS Conference in Bangkok, Thailand in 2004. The main reasons for the protesting included concerns about the level of health care for the volunteers before and after the trial; the apparently low level of counselling the volunteers were receiving before their trial; and the possibility that the volunteers might not get treatment if they became infected with HIV during the study. Family Health International (FHI), who led the trials, reassured that the FHI protocols would provide antiretroviral therapy if anyone did become infected. Similarly a study of 400 sexually active women in Cameroon was halted by Cameroon’s Minister of Public Health in 2005. FHI agreed to comply with the Ministry’s recommendations, stating that “the safety and welfare of study participants is FHI’s highest priority.”

There is a very good link that I have found that lucidly explains their distinction and degree of effectivesness, and how they might be used in the future to tackle down the spread of HIV.

Visit: Are PEP and PrEP effective in preventing HIV transmission? Who might benefit from them?

via Post exposure prophylaxis (PEP) and pre exposure prophylaxis (PrEP).

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