Infectious diseases specialist Kevin Rebe spoke to Bhekisisa editor Mia Malan about the do's and don'ts of pre-exposure prophylaxis, known as PrEP. Rebe heads up Anova Health Institute's PrEP demonstration projects.
1. What is PrEP?PrEP is a strategy of taking a two-in-one tablet that prevents HIV infection if you're exposed to the virus. Only people who are HIV negative should use PrEP.
2. How does it work?The pill, called Truvada, contains two antiretroviral drugs, tenofovir and emtricitabine. (These drugs are also used to treat people who are HIV infected.) Once there is a high enough level of those two medications in an HIV-negative person's vaginal or anal tissues, the drugs are able to, most of the time, shield the immune system cells from being infected by HIV when exposed to the virus.
3. How effective is the pill?The latest PrEP study that was done among men who have sex with men showed protection levels of about 90%. In some of the earlier studies protection was lower, particularly among young women, because trial participants didn't take the medication often enough. Real-world demonstration projects have shown protection levels even higher than 90%.
4. How often do you need to take the pill?You need to take it once a day. Without being neurotic about it, it should be taken at a similar time every day. That doesn't mean that taking the pill has to be on the minute – there's probably a few hours leeway either way.
5. What happens if you miss a dosage?The rate of protection is directly related to the rate of pill taking. If you don't take the pill correctly, you don't get optimum protection. Studies have shown that people who take four PrEP doses a week still get protection, but less than people who take it daily. Aiming for daily doses is the best strategy.
6. Do you need to take the pill lifelong?No, you would take it only through a period of risk. Let's say you're a young, female student who is not in a relationship. If you're dating a couple of people through your university years, and have sex with them, you'd want to take PrEP daily throughout your university years. But when you meet your future husband and you're in a closed, monogamous relationship, you would stop taking PrEP.
7. Can you take PrEP for one night only?No. You need to take the pill once a day for about a month before it protects against vaginal sex for people that are having receptive vaginal sex. It takes about a week, if taken daily, to protect against HIV infection through anal sex.
8. How would you know if you need PrEP?HIV-negative people who have a risk of being exposed to HIV should consider taking PrEP. For example, if somebody is in a monogamous relationship, and both partners are HIV negative, PrEP wouldn't be necessary. But if you're in a discordant relationship, where one person is HIV negative and the other HIV positive, it will be wise to consider PrEP.
In South Africa, adolescent girls and young women, commercial sex workers and men who have sex with men have a higher risk of contracting HIV than the general population. If we're to start preventing HIV infections by using PrEP, we should target these three population groups first.
9. Does PrEP also protect you against other sexually transmitted infections?No. It only protects against HIV infection. It also doesn't safeguard you against falling pregnant. That's why you still need to use condoms and other forms of contraception.
10. Can you use PrEP and oral contraception together?Yes. There would be no interaction between the two.
11. Is it safe to fall pregnant with PrEP in your body?We don't know. Tenofovir is potentially toxic during pregnancy. There are small, but existing, risks of kidney dysfunction in the newborn. The Medicines Control Council in South Africa has actually listed pregnancy as a contra-indication to using Truvada for PrEP.
12. Does the pill have side effects?Nine out of 10 people in any PrEP trial experienced no side effects. Side effects included minor gastro-intestinal issues such bloating, nausea, flatulence and reduced appetite. The side effects disappeared within the first few weeks.
Another side effect is kidney dysfunction. Tenofovir is excreted out the body through the kidneys. This could challenge the kidneys slightly. A medical professional would have to test that your kidney function is normal and monitor it throughout your use of PrEP.
At Anova's clinics we haven't found kidney dysfunction to be a significant problem among PrEP users.
13. Can your GP prescribe PrEP?Yes, because PrEP has been approved by South Africa's Medicines Control Council. You can't go to the chemist and request PrEP over the counter without a doctor's prescription. Your GP would first have to test you for HIV and make sure you're HIV negative.
The doctor would also take a sexual history and assess your HIV infection risk. If you have a sufficient risk, your doctor will counsel you about safer sex, so that you understand the need for condom use and other safer sex practices in combination with PrEP.
14. Would your medical aid pay for PrEP?Medical aids are starting to look at covering PrEP. Fedhealth already covers it for an initial period of six months for members who have self-identified that they are at a high risk of contracting HIV or an HIV-negative person in a relationship with an HIV positive person.
15. How much does a month's supply of PrEP cost?If you buy it retail, it is about R600. A generic, which will soon be available, will cost about R200 to R220 a month. The health department will hopefully be able to purchase in bulk at preferential tender prices.
16. Is PrEP available in the state sector?No, not yet. It will soon be made available to sex workers at selected clinics.
17. Does PrEP make people promiscuous?This is one of the things that worry researchers and scientists. Will people make their behaviour more risky because they think they are protected and safe on PrEP? So, will they have more sex partners? Will they drop the condoms?
The best way to answer this question is to go back to the evidence of the PrEP trials. None of those trials has shown that people increase their risk. Trial participants didn't stop using condoms; their sexually transmitted infection rates didn't go up.
18. What happens if you take PrEP if you're HIV positive?Truvada could potentially not work for you as HIV treatment. Having both the virus and medication in your body allows the virus to become resistant to the medication.
HIV-infected people use at least three types of antiretroviral drugs simultaneously to make it difficult for the virus to figure out how to become resistant to the drugs.
It is important that your HIV status is confirmed as negative before you take PrEP. There is a window period of four to eight weeks after HIV infection during which an HIV antibody test can't detect your infection, because your body hasn't yet manufactured HIV antibodies.
Somebody who is on PrEP, but doesn't take the medication correctly, could become infected with HIV because there might not be enough PrEP in their bloodstream to prevent HIV infection. In that case, resistance can also develop.
19. Is Truvada the only antiretroviral drug that would work for PrEP?Truvada-based PrEP is just the first rung on the ladder. We started with Truvada because it's a once-a-day pill, easy to store, widely available, causes minimal predictable side effects, and it's powerful enough to control HIV. But trials with other antiretroviral drugs are underway.
The ideal would be to use separate antiretroviral drugs for PrEP and HIV treatment, so that the possibility of resistance is eliminated.
20. What could PrEP look like in the future?We will not only be looking at new drugs to trial to see if they work as prevention, but also at new delivery methods. The answer might be injectable PrEP. For women, perhaps what we need is a bimonthly two-in-one injection consisting of a contraceptive and PrEP, then you don't have to worry about taking a pill every day.
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