Post and Pre-Exposure Prophy-laxis: How Effective Are They?

by Bill Buchanan, Clinic Coordinator of the Pitt Men’s Study

I remember a more genteel and demure time when people, if they had to refer to condoms (and they tried not to), called them prophylactics. We use prophylaxis all the time, whether it’s that annual flu shot, buckling up in the car, looking both ways before crossing the street, or using a condom when having sex (whether to prevent pregnancy or avoid a sexually transmitted disease).

When a possible exposure to HIV occurs, one can take highly-active antiretroviral therapy (HAART or drug cocktails) in an effort to try to stop the establishment of an infection. This method of prophylaxis has been used in the medical community as a way to prevent HIV infections, and it has proven to be fairly effective following accidental work-related exposures such as needlesticks. We call this Post-Exposure Prohylaxis or PEP.

Important caveats with PEP are that medications must be started as soon as possible after the exposure and that PEP is not 100%effective. People usually stay on PEP for a month, and can experience the side effects (not to mention the expense) associated with these potent medications. PEP’s not perfect, but it does cut the number of infections from work-related, accidental exposures and is an accepted medical practice.

What is not entirely clear is how effective PEP is in preventing infection after a sexual exposure. Our recommendation is to use condoms correctly and consistently, and should an accidental sexual exposure occur, get into care immediately either by calling your doctor or going to an emergency room where you    can be evaluated. PEP should never be seen as a substitute for safer sex practices – it is at best a backup for when safer sex practices fail.

Another strategy, PrEP (or Pre-Exposure Prophylaxis), made the news a few months back when the results of an interesting but controversial study were released. Men who have sex with men and transgendered women were given the anti-HIV oral drug Truvada to take daily in the hope that by having the drug in their systems it would reduce their risk of infection if safer sex
failed. The trial reported a reduction in HIV infections of 44% in the main analysis, but in sub-analyses it was reported that adherence to the drug critically affected the degree of protection.

That sounds better than nothing until you realize that condoms are 95% effective when used correctly and consistently. If you look at those numbers a different way: approximately 60% of those who took the drug got infected anyway. Additional drawbacks to oral PrEP in the US are:

• The expense (almost $40 a day and probably not covered by insurance).

• Finding a doctor willing to prescribe it.

• Having to take a very potent medication daily (and dealing with the possible side effects).

• Its potential ineffectiveness if one is exposed to drug-resistant strains of HIV.

• PrEP has no effect on the transmission of other sexually transmitted diseases like a condom does.

• Worth repeating – its effectiveness is far less than that of condoms (which are cheap and readily available).

Our recommendation is that people not use oral PrEP. Until an effective HIV vaccine is found, condoms and other risk reduction methods are the best bet to avoid HIV infection. The staff of the Pitt Men’s Study is more than willing to discuss safer sex, risk reduction, PEP and PrEP with you at your next visit (or call us at 412-624-2008 or 1-800-987-1963), and free condoms and
lube are available at our clinic.

If this were that more genteel and demure time, I would pour you a cup of Earl Grey in a cup of Lenox china and chat. But there’s no time for all that civility. Condoms: 95% effective. PrEP: approximately 60% ineffective. Do the math.


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