Spotlight Center on HIV Prevention Today


Zero HIV Infections When PrEP Is Taken 4 or More Times a Week

July 24, 2014

Tenofovir/emtricitabine (Truvada) as PrEP (pre-exposure prophylaxis) reduced HIV risk by 100% for all patients who took it at least four times a week, according to results presented by Robert M. Grant, M.D., M.P.H., at the 20th International AIDS Conference (AIDS 2014) in Melbourne, Australia.

The iPrEx Open-Label Extension (OLE) aimed to confirm the effectiveness of PrEP, while identifying demographic and behavioral characteristics associated with PrEP uptake and adherence.

Even though tenofovir/emtricitabine was approved by the U.S. Food and Drug Administration (FDA) for use as PrEP in 2012, uptake has been slow. Between January 2012 and September 2013, only 2,317 patients (half of whom were women) filled prescriptions for tenofovir/emtricitabine as PrEP in the U.S., according to Grant.

The study enrolled 1,603 HIV-negative men and transgender women who have sex with men, all of whom had previously participated in PrEP studies. They were offered 72 weeks of oral tenofovir/emtricitabine as PrEP, with about 76% opting to take the pills and about 23% choosing to participate in the study without taking PrEP at all.


No participant who took PrEP four or more times a week became HIV positive. For those who took the pills two or three times a week, the HIV risk reduction was 84%, showing that adherence doesn't necessarily need to be perfect in order for PrEP to be effective.

However, despite the strong interest in and effectiveness of PrEP, only 5% of participants actually took the pill every day, while only 22% took the pill four to six times a week.

The study measured the use of PrEP by analyzing dried blood spot (DBS) samples, an innovative and sensitive technique for determining long-term PrEP use. Among those taking PrEP, HIV incidence was:

  • 4.7/100 person-years if no drug was detected in DBS.
  • 2.3/100 person-years if DBS indicated less than two tablets a week.
  • 0.6/100 person-years if DBS indicated two or three tablets per week.
  • 0/100 person-years if DBS indicated four to seven tablets per week.

PrEP uptake was 6% higher for those who participated in condomless receptive anal sex (81% versus 75%; P = .003). There was no difference in PrEP uptake by age, education, transgender status, or use of alcohol, methamphetamine or cocaine.

Moreover, looking at drug concentrations in DBS, adherence was higher in those who engaged in condomless receptive anal sex, had multiple sexual partners or had a history of syphilis or herpes.

For the 23% (378 people) who opted not to take any PrEP during the study, the reasons included:

  • I am concerned about side effects from the pills (50%).
  • I don't want to take a pill every day (16%).
  • I don't like taking pills (13%).
  • I can avoid HIV in other ways (14%).
  • I am concerned that people will think that I am HIV positive because I am taking tenofovir/emtricitabine (7%).
  • I am concerned that people will know that I have sex with men and/or transgender people because I am taking tenofovir/emtricitabine (3%).

Despite speculation that being on PrEP would lead to "risk compensation," or an increase in riskier sexual behavior, the opposite was observed. Sexual practices among both groups in the study became safer, based on self-report. Syphilis incidence, a marker of sexual risk behavior, was similar between both groups.

The results from this study show a strong interest in PrEP among men and transgender women who have sex with men, particularly those at increased risk for HIV, as well as high levels of effectiveness of PrEP with less than perfect adherence.

[UPDATE 7/31: This article has been updated to add information regarding PrEP adherence rates among iPrEx study participants.]

Warren Tong is the research editor for and

Follow Warren on Twitter: @WarrenAtTheBody.

Copyright © 2014 Remedy Health Media, LLC. All rights reserved.

This article was provided by TheBodyPRO. It is a part of the publication The 20th International AIDS Conference.

Reader Comments:

Comment by: Scott (Buffalo,ny) Mon., Aug. 11, 2014 at 10:39 am UTC
I am ashamed of the attitudes on here. I take Truvada every day. It has the least side effects. Doctors should be sued for not telling their patients about an FDA approved treatment for preventing HIV.

The moderators should stop the personal attacks.

How can we really talk when people are attacking each other.

This is worse than when the Pill came about.
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Comment by: Mike (Albany) Thu., Sep. 25, 2014 at 8:37 pm UTC
I'm ashamed that this website that has forsaken the welfare of people who don't or can't obtain Truvada, as well as people who are HIV+, all in favor of imaginary victims of "slut shaming".

Comment by: tarisa moyo (bulawayo) Thu., Aug. 7, 2014 at 12:38 pm UTC
What is the cost for one week dosage and where is this PrEp medicine obtainable?
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Comment by: michael (los angeles) Tue., Aug. 5, 2014 at 9:07 am UTC
gee...i wonder if the reason it is not gaining os much traction is because truvada is still on patent and costs one thousand dollars a bottle. i guess they have to push it while it still on patent because once they can no longer keep it on patent, there goes the bottom line for the shareholders.

one way or another , these pharmas will get their money...if you are poor, they will get every penny from government programs and charities that they can without a second thought. health care is not about helping people...if that was the case, the cost would not be an issue......but it is, so what does that tell you?
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Comment by: Observer Sat., Aug. 2, 2014 at 2:53 pm UTC
Does the discourse about PrEP make sense? Nope. Let's take this article: For the life of me, I can't imagine how a group can claim to want to end the spread of HIV with PrEP, but advertise minimal adherence thresholds, knowing full well that people will aim for that and come up short.

People have been screaming about PrEP since well before it was in the spotlight. The bad science and relentless PR behind this new use for an old drug are too conspicuous for a reasonable person to ignore. The long term, population-wide utility of chemoprophylaxis is, at best, unproven. It appears that thought leaders who've said this have been marginalized for speaking out. Phrases like "slut shaming" are now magic words to shut down discussions in favor of a narrative that demonizes diagnosed HIV positives as infectious time bombs and validates the idea that gay men are incapable of keeping their pants on. Somehow, we're all supposed to believe this fights stigma. Orwellian is an apt description.

As near as I can tell, there is a trail of money connecting every organization advocating PrEP to Foster City. This is an obvious conflict of interest.

We should absolutely be suspicious. In fact, it is increasingly obvious that PrEP users, and probably gay men of every status, are somehow being set up to fail. In the words of one online commenter, "I've read this book before, it's called And The Band Played On".

This drama also echoes a more classic work, "The Emperor's New Clothes". In order for the obvious to be acceptable, it must be stated simply and without judgement.

Prattling on about how "most gay men remain negative" on a website read by positive people is tone deaf. It's also counterproductive to tell gay men that a drug cast as their only hope for remaining negative is "a party drug", even if partying is the only conceivable real world application. There are serious arguments against PrEP. For them to be heard, they shouldn't be shrill.
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Comment by: Mike (Sacramento, CA) Fri., Aug. 1, 2014 at 6:23 pm UTC
I think the problem is expense. Are most drug plans authorizing Truvada for this use? Even if covered, co-pays are prohibitive for most people.
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Comment by: Steve (Emeryville, CA) Thu., Aug. 7, 2014 at 5:05 pm UTC
Mike - You're being a bit short-sighted. Truvada, on a drug plan, co-pays is so much less than having to pay for what you'd need if you were HIV+... not including the lab fees and the doctors fees and traveling back and forth and more than likely missing work, which could endanger your job.
Comment by: Observer Mon., Sep. 1, 2014 at 1:58 pm UTC
No, it is not "much less", it's basically the same combination used by people who are already positive. Since Truvada and other fixed dose antiretroviral medications are all on the same tier of any drug plan, and since everything has been reduced to a single pill, the copays are the same whether you're taking Truvada or Complera.

Probably one of the most bizarre myths that surrounds all this noise is that Truvada is not, in fact, 2/3 of a typical ARV course, requiring very similar commitments of time, money and medical care. Stop trying to suggest to people that Truvada is aspirin but HAART is chemotherapy, "so you better get on the pill now before your life is over". They're the same thing! Both require similar labs, both require doctors' appointments and missing work "that could endanger your job".

I swear, when people shoot their mouths off about this stuff like it's Prilosec, they just betray their ignorance and bias. You can't have both stories. You can't tell people that living with HIV is an unmanageable quagmire of doctor's visits and endless pills, but life with Truvada is a leisurely and relaxing. Not only is it grossly offensive to people who are actually managing the virus, but it's a misrepresentation to a people who are weighing their options in taking chemoprophylaxis.
Comment by: Myles Helfand ( Thu., Sep. 4, 2014 at 10:40 am UTC
For clarity, I just want to note here that Truvada is not considered potent enough that it can be used by itself to treat HIV in people who are already living with the virus. It appears to do a bang-up job at reducing a person's risk for infection if they should be exposed, but if a person becomes HIV positive, they'll want to take a full regimen, which usually consists of three or four different drugs (typically taken as a single pill).
Comment by: Observer Mon., Sep. 8, 2014 at 8:05 am UTC
What was the point of letting us know that Truvada is not "potent" enough to treat HIV, but to underscore the suggestion that I'd previously taken offense to? I'm well aware that Truvada, by itself, isn't used to control a full HIV infection, as are most people who are diagnosed and all who prescribe. Most regimes require a third component. Occasionally, a fourth. Typically, that third component is an integrase inhibitor which is even less likely to incur side effects than Truvada.

I understand that this site makes money off web ads from pharmaceutical companies, and I understand that BigPharma has a vested interest in selling this drug to the negative via an endless series of infomercials that are somehow not technically "advertising". When you sell this drug, please don't perpetuate the myth that life with HIV is some sort of nightmare of doctors' visits and copays, but life with just Truvada is puppies, casual sex and disco dosing. When you create that contrast, you're selling this drug on the back of stigma. I, and every other HIV positive person, has a right to be furious and to question your honesty and commitment to people who are producing antibodies.

As a website that purports to spread knowledge and reduce stigma, you have a primary duty to be honest in your reporting and your representation of life with this disease. To be clear, "honesty" is not drawing some imaginary line between Truvada and "HAART" to scare people into PrEP usage. You are also obligated to be accurate. That means finding a better way to sell PrEP than telling people that if they do test positive, they'll lose their jobs, spend the rest of their life in some waiting room and wind up demented at 42, so they need to immediately hop on the Truvada bandwagon, which is suggested to be free of any consequence.

As nuts as some of the anti-PrEP zealots are, at least they're consistent and honest. I wish I could say the same for Team Pharma.

Comment by: andy (new york) Thu., Jul. 31, 2014 at 8:13 pm UTC
This is not science. How often were they exposed? You said in the last paragraph they weren't riskier while on PrEP so how do you know the PrEP kept them neg? They had remained neg all the years prior without PrEP and you admitted they used condoms even more. 80% of gay men have stayed neg without PrEP. For the millions of us taking nothing has resulted in 0 infections and by your logic makes taking nothing 100% effective. Orwellian.
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Comment by: chadwick carter (pensacola) Wed., Jul. 30, 2014 at 5:47 pm UTC
Is this a pill I must take for the rest of my life? What are my chances of seroconverting if I stop taking them after 6 months?
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Comment by: tagesreste (Oregon) Fri., Aug. 1, 2014 at 4:18 am UTC
You can take it when you feel like it. It's not lifelong. Ideally, you'd take it during periods of high sexual activity with multiple partners. It's not necessary during a monogamous relationship unless you need that extra protection or have an open relationship. Your chances of seroconverting return to 100% after you stop taking the drug longer than a week. It starts at 99% after taking it for a week straight, has a half-life of one or two days, and then drops in effectiveness with each missed pill after. It's not a long-term drug unless you consistently take it.

Comment by: Billy (Charleston, SC) Wed., Jul. 30, 2014 at 5:14 pm UTC
This is nice to know my partner is HIV+ I am HIV - as I know of we have had a few miss haps since I was tested last. But when we talked with his doctor about prevention all he said was use condoms. Nothing about this drug just use condoms. I'm going next week to get tested to see if I'm still HIV-. If I'm not then can I sue my partners doctor for not letting me know about this drug. From the reports on the web this drug has been out for a few months.
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Comment by: Jason (Toronto, ON) Thu., Jul. 31, 2014 at 6:24 am UTC
Are you fricking kidding me. Sue your doctor if you're HIV+?
Your dr advice is correct. Use condoms if you want to be sure you don't get HIV. You can't sue him just because some study results released after the fact show efficacy of PrEP. Ridiculous.
Comment by: michael (los angeles) Tue., Aug. 5, 2014 at 9:20 am UTC
sue your doctor?

so let me get this straight. you are knowingly sleeping with an HIV positive partner of your own accord, and you want to sue the doctor if you become positive when he gives you the correct advice?

tell you something, i don't even think you can afford this drug if your doctor tells you about costs about a thousand dollars a bottle.

and no, this drug has not been around a few's been out for years.

oh hell, i'll rant on this one. i'll say what others are thinking but refuses to probably won't get posted by the mods anyway.

you are an idiot and you sicken me. that attitude of suing your doctor is a great example of your stupidity. basically, your logic is you buy a gun and play with it and if you shoot yourself, you will sue the store for not telling you not to shoot goodness, what would you do if he told you that the safest thig to do is not have sex and you still do anyways, who do you blame then?.....but
Comment by: Bill (oceanside, ca) Tue., Aug. 5, 2014 at 1:58 pm UTC
The original post so sad, I don't even know where to begin. So many the poster able to access drugs but not the partner, or has the poster just been sold the idea that this is a "good option for serodiscordants", without hearing the word that the risk from a treated + is low to nonexistent? Have you been tested and cleared of all STDs for your partners benefit, or is he just automatically the only risky party since he has "AIDS"? Since when is HIS doctor obligated to care for the health of anyone but HIM anyway? The OP sounds like a nightmare. Do your partner a favor and break up with him!
Comment by: Michael (Denver, CO) Wed., Aug. 6, 2014 at 12:47 pm UTC
WTF?!? You sat in on a meeting between your partner and his doctor, demanded a prescription that you don't know the first thing about from someone who is not charged with your medical care and threatened a lawsuit when he told you to take a hike? No, you can not sue him for malpractice. In order to even consider that, the doc in question would have to be responsible for you.

You've pretty much nailed every stereotype of the self-absorbed worried well negative partner. I don't think the picture you've painted would be more alarming if you'd literally grabbed the Complera out of your husband's hands and announced that your "peace of mind and good sex" matter more than his life. You sound like the partner (and the patient) from Hell. Just so you know, when people voice concerns about the direction the PrEP debate is taking, they envisioning people like you.

Again, your partner's doctor is not your own. Do them both a favor and remove yourself from the equation.

Comment by: Brendan (Pittsburgh, PA) Wed., Jul. 30, 2014 at 12:22 pm UTC
I'm very happy to see such research put into this, but it's not possible for the 378 people that opted out of pill taking to add up to 103%.
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Comment by: Myles Helfand ( Thu., Sep. 4, 2014 at 10:41 am UTC
Percentages are rounded. :)

Comment by: JUAN (MEXICO) Thu., Jul. 24, 2014 at 1:03 pm UTC
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