HIV Pre-Exposure Prophylaxis

Situation

Harry and Gon were watching the news last night when “HIV pre-exposure prophylaxis” was being discussed. Both Harry and Gon had not heard about this before even though they both had studied HIV and AIDS a lot at CXC Biology.

Harry began to think about what he had done in the past year while working for off shore oil companies in Africa. He often bragged about how many ladies he had sex with there. He did not often use protection as he hated the reduced feeling.

Harry believed he was at low risk though as he only engaged in vaginal sex. He began to wonder if this HIV medication became available in his home country, whether more persons would engage in sex without condoms and spread diseases.

What is Pre-Exposure Prophylaxis (PrEP)?

is medication which is taken before sex to prevent getting HIV in persons who are at high risk of coming into contact with the virus.

Does it work?

Yes.

If Harry took PrEP it would reduce his risk of HIV transmission by over 85%. (1, 2)

Why just not use condoms?

Harry should!

Most studies which test the effectiveness of HIV PrEP, also advise condom use because condoms are very effective in preventing HIV.(6) There are many things which make condoms a better choice to only using PrEP:

• If Harry took PrEP it would not affect his chances of getting other STDs (sexually transmitted diseases) including Gonorrhoea, Syphilis, or Chlamydia.
• PrEP also does not prevent Harry from impregnating another.

However, PrEP is specifically targeted for persons who engage in risky behaviour. (3, 5) While a detailed sexual history and assessment is needed by a doctor, persons described as at risk include:

• Straight men like Harry who do not use condoms often and have sex with female partners from a place with high HIV prevalence (e.g. sub-Saharan Africa).
• Men who have sex (without condoms) with multiple male partners.
• Men and women who have a sexual partner with HIV (with detectable viral load).

Won’t persons just choose PrEP and engage in risky behaviours if it becomes widely available?

No.

The evidence at present suggests that persons are not likely to engage in more risky behaviour if PrEP becomes available. Several studies note PrEP did cause more risky behaviour with levels of other STDs and condom use not being much different. (1,5)

In addition, it is important to highlight that the medication is aimed at persons who are already engage in risky behaviour. There are reasons why PrEP is not a perfect solution to prevent HIV for Harry:

• It is not a cure or vaccine for HIV.
• It is not “a morning after pill” and takes a while to work.
• It would require Harry to take the medication every day to work best. (4)
• A doctor may not prescribe PrEP for many other reasons. For instance, if Harry had kidneys which are not working normally he may not get the medication. Harry would also need regular testing while on the medication. (5)
• Lastly, the medication does have some side-effects.

Should countries in the Caribbean offer PrEP?

Perhaps.

The World Health Organisation recommends HIV PrEP. (7) Some countries have followed this advice because of the compelling evidence. However, other countries including UK, have replicated the studies but there has not been a national drive toward making PrEP widely available (at the time of this article). (8)

Where can I get more information?

Further information (video and text) resources can be found at:

• American sources: http://www.whatisprep.org/
• British sources:  http://www.tht.org.uk/sexual-health/About-HIV/Pre-exposure-Prophylaxis#    and https://www.england.nhs.uk/2016/03/prep/
• World Health Organisation: http://www.who.int/hiv/pub/prep/who-unaids-prep-2015.pdf

References:

1. McCormack, Sheena, et al. “Pre-exposure prophylaxis to prevent the acquisition of HIV-1 infection (PROUD): effectiveness results from the pilot phase of a pragmatic open-label randomised trial.” The Lancet 387.10013 (2016): 53-60.
2. Anderson, Peter L., et al. “Emtricitabine-tenofovir concentrations and pre-exposure prophylaxis efficacy in men who have sex with men.” Science translational medicine 4.151 (2012): 151ra125-151ra125.
3. Dolling, David I., et al. “An analysis of baseline data from the PROUD study: an open-label randomised trial of pre-exposure prophylaxis.” Trials 17.1 (2016): 1.
4. Seifert, Sharon M., et al. “Dose response for starting and stopping HIV preexposure prophylaxis for men who have sex with men.” Clinical Infectious Diseases 60.5 (2015): 804-810.
5. Grant, Robert M., et al. “Preexposure chemoprophylaxis for HIV prevention in men who have sex with men.” New England Journal of Medicine 363.27 (2010): 2587-2599.
6. Weller, S. C., and K. Davis-Beaty. “Condom effectiveness in reducing heterosexual HIV transmission (Review).” The Cochrane Library 4 (2007): 1-24.
7. World Health Organization. “Guidance on oral pre-exposure prophylaxis (PrEP) for serodiscordant couples, men and transgender women who have sex with men at high risk of HIV: recommendations for use in the context of demonstration projects, July 2012.” (2012).
8. Gold, Deborah. “Stop stalling and make PrEP for HIV available now.” BMJ353 (2016): i3160.