Possible rare case of transmission of HIV resistant to Pre-exposure Prophylaxis (PrEP) medication

HIV Pre-exposure Prophylaxis, better known as PrEP, has changed the lives of many people around the world by providing a way for people who are HIV negative to decrease their risk of acquiring HIV infection.

Hundreds of thousands of people globally are currently taking PrEP, including over 6500 people in King County alone. To date, just four cases of possible PrEP failure have been reported in the medical literature or at scientific conferences. In King County, a community medical provider recently notified Public Health of a man with newly diagnosed HIV infection found to have a virus resistant to both of the medications in the PrEP pill, which is called Truvada.

Photo courtesy Avert.org

We talked with Dr. Matthew Golden, MD, the Director of Public Health’s STD/HIV program, to learn more. In the blog below, we also include comment from John Doe, a sex partner of the man who was infected, whom the STD/HIV staff contacted as part of the investigation.

Dr. Golden, before we get into the details of this new case, tell us more about PrEP.  What is Truvada?

Truvada is a pill that people who are HIV negative can take to decrease their risk of acquiring HIV infection. This is called HIV pre-exposure prophylaxis, or PrEP. Truvada contains two medications, tenofovir and emtricitabine, both of which are also used to treat HIV in people who are HIV positive.

How effective is Truvada/PrEP in preventing HIV infection?

PrEP is very effective. If taken consistently, it reduces the risk of acquiring HIV through sex by over 90%, and perhaps by over 95%. It is also more than 70% effective in preventing HIV infections transmitted through sharing injection equipment. So while it is very effective, like many drugs, it is not 100% effective.  As the letter below from John Doe illustrates, this is something that all people on PrEP should understand.

How does a person on PrEP get infected with HIV?

This is a complicated question.  As you mentioned in the introduction, hundreds of thousands of people around the world are currently taking PrEP, including over 6,500 people in King County alone. PrEP failure is very rare, at least in people who consistently take their medication.

  • HIV acquisition while on PrEP can occur in several ways:
  • By having sex or sharing injection equipment with someone who has an HIV infection that is resistant to the medications in PrEP and who is not taking effective treatment to suppress the virus;
  • By taking PrEP inconsistently during times of potential exposure to HIV; In very rare instances, PrEP may just not be effective, meaning an individual who is consistently taking their medication becomes infected with a virus that is not PrEP resistant.

Also, if someone starts on PrEP while acutely infected with HIV they can develop a PrEP-resistant infection.

Tell us more about this new case in a King County resident.  

A man newly diagnosed with HIV likely became HIV infected while taking PrEP. The man reported sex only with other men, and both he and his medical provider indicated that he had consistently taken daily PrEP in the months since his last HIV negative test and prior to testing HIV positive.

The virus he is infected with is resistant to both of the drugs contained in Truvada.  He may have been infected by a multidrug resistant form of HIV, though we don’t know for sure. As I said, this has been reported before.  It’s very rare, but we have identified one prior case in King County of possible PrEP failure in a person with a resistant infection. It’s important for people to be aware that PrEP is not 100% effective.  It’s very effective, but not 100%.

What is Public Health doing about this case? 

Public Health, as well as the infected man himself, have attempted to notify his sex partners, and to date none have tested positive for HIV. However, he did not have information to contact all of his partners, so some of them don’t know about his infection.  It is possible that one of them has a PrEP-resistant infection, and that person may expose others to that infection.  We continue to investigate this new case, and to conduct ongoing work to identify persons with Truvada-resistant HIV infection and ensure that such persons receive effective treatment. You can learn more about what we’ve been doing in King County in the 2017 HIV Surveillance Report and in a recent article on AIDSMap .

So documented cases of PrEP failure are very rare, but they can happen. As part of the investigation of this case, you contacted John Doe (a pseudonym), who was a sex partner of the man who got infected while on PrEP and advised him to get an HIV test. He was unaware that he was at risk for infection while on PrEP, and asked us to include in this blog the following letter from him to his community:

To My Community, 

This experience has shaken me to my core. I had sex with the Seattle man that later tested positive for the PrEP resistant strain of HIV. I am a gay man who nearly contracted HIV while on PrEP. I had condom-less sex with a man I didn’t know at all and I had asked him the questions I thought were relevant. He tested HIV negative within two months of the time we had sex. I thought I was in the clear. I’m also a mathematician and I thought I understood the risk associated with my sex life while on PrEP. I didn’t. 

So what have I learned?  A lot, in the few days since I received a terrifying phone call asking me to get tested. Thankfully, it was negative. I thought only three people had ever been infected with HIV while taking PrEP, and there was no real risk of exposure to a PrEP-resistant strain of HIV here in Seattle. I thought PrEP pretty much eliminated my risk of infection. I was wrong.  In fact, PrEP resistant strains of HIV are circulating in my community. I take my medication every day without fail but this doesn’t give me full protection. It can’t do that. PrEP can fail for many more reasons than I thought. I made a really important decision about my life without all the facts. 

I want to live in a world in which I don’t have to think about becoming positive and I thought PrEP had created that world. I now know that’s wrong.  I will stay on the medication because it lowers my risk of HIV infection, but I’ve made my personal decision to do more to stay safe. What do you think is best for you? 


John Doe 

What does this mean for the man who is infected with a resistant form of HIV?

PrEP-resistant infections are still treatable. Although the simplest first-line treatments will not work against this man’s virus, he is being treated with alternative medications, and I think the likelihood is very high that he will become virally suppressed and  do well long-term.

If PrEP isn’t 100% effective, what do people on PrEP need to do to be sure they are not HIV infected?  

People on PrEP should test for HIV and other sexually transmitted infections every three months. If they develop a flu-like illness with symptoms such as fever, sore muscles, sore throat, and fatigue they should contact their medical providers for HIV testing, or come to the Public Health STD Clinic at Harborview for evaluation.

Everyone should have a plan to minimize their risk of acquiring HIV and other sexually transmitted infections (STIs). How to do that is an individual choice that each of us needs to make for themselves based on our values, willingness to accept risk, and good information. For many people, the right plan is one that employs a variety of different strategies.  PrEP is one of those strategies.

Who should be on PrEP? 

If you have a sex partner who is HIV infected and he or she is not taking HIV medications or is not virally suppressed (i.e. undetectable), you should be on PrEP.  Likewise, if you are a man who has sex with other men or a trans person who has sex with men and you’ve had rectal gonorrhea or syphilis in the last year, use methamphetamine or poppers, or exchange money or drugs for sex, you should be on PrEP.  All sexually active MSM and trans persons who have sex with men who aren’t in a long-term, mutually monogamous relationship with someone of the same HIV status should at least talk to their medical provider about PrEP. Other people concerned about their HIV risk should also discuss PrEP with their medical provider. If you aren’t certain how to get PrEP, talk to your medical provider or come to the STD clinic at Harborview and we’ll help set you up.

What can people do to reduce the risk of contracting sexually transmitted infections (STIs), including HIV, whether or not they are on PrEP? 

PrEP does not protect people from STIs like syphilis, gonorrhea, herpes, chlamydia, and human papillomavirus. Rates of gonorrhea and syphilis are rapidly climbing in King County and, among MSM, we are currently experiencing an STI epidemic of unprecedented size.

Condoms are a critically important tool because they are effective against all of those infections, and they protect against HIV, including the very rare cases of PrEP-resistant HIV.

I realize that using condoms all of the time is not a realistic goal for everyone.  But the choice isn’t all or nothing, and most people at significant risk for STIs use condoms at least some of the time.  People should ask themselves, could I increase how often I use condoms?  Here are suggestions:

  • Using condoms with non-regular partners or for the first weeks or months of a new relationship is a good strategy for some people;
  • Decreasing one’s number of partners;
  • Choosing safer behaviors, like oral sex, instead of more risky behaviors, like receptive anal sex, at least with partners one does not know well;
  • Adjusting one’s behavior based on knowledge of a partner’s HIV status, HIV testing history, and HIV viral suppression.

The key is to have a good strategy for minimizing your risk of HIV and STIs, to stick with your strategy when it’s working, and to adjust your strategy when you realize that it’s not working.

It sounds as though PrEP has made an enormous difference to people at risk of contracting HIV. As King County’s STD/HIV Program director, what difference do you think PrEP has made?  

You have to think about this in terms of the difference PrEP’s made for individual patients and the difference it’s made for the community as whole.  Lots of people in King County, particularly lots of men who have sex with men (MSM) and a fair number of transgender people, are taking PrEP. We estimate that about one in five HIV negative sexually-active MSM in King County are now on PrEP, with higher levels of use among MSM who are at higher risk of acquiring HIV. For many people, PrEP really buys them peace of mind, a sense that they’re protecting themselves, taking control of their sexual health, and doing something for their community. That sense of control and protection is really powerful, and it’s grounded in good scientific evidence.

From a community perspective, it’s harder to know how much PrEP has decreased HIV transmission. It’s too early to know for sure. That said, the rate of new HIV infection among MSM in King County is going down, and we think that PrEP is one factor contributing to that decline.

What’s the number for the STD clinic?  

Find us at 206-744-3590 and on our website. We welcome anyone of any age who is interested in protecting themselves against STDs, or who thinks they may be infected.  Or you can click here for list of medical providers who prescribe PrEP.

Public Health continues to recommend PrEP as a highly effective way to diminish the risk of acquiring HIV.  Local guidelines on who should take or considering taking PrEP are available at our PrEP website.

Originally posted on March 12, 2018


4 thoughts on “Possible rare case of transmission of HIV resistant to Pre-exposure Prophylaxis (PrEP) medication

  1. I tell every patient I start on PrEP that PrEP is 99+% effective when taken every day or close to every day. It is not 100% effective. We expect that these cases will occur, though rarely, in people with excellent adherence. It is important to remember that PrEP protects far far far more many people from acquiring HIV than will be outweighed by the few people who acquire HIV despite taking PrEP.

  2. I’m struggling to understand what you mean to accomplish with this warning, in particular by circulating the anonymous letter from “John Doe.” It is the reflexive reaction of a man who seems to have an outsize fear of HIV (“shaken to the core”… “terrifying”…) And this from a man who did not contract HIV.

    He has apparently internalized an irrational fear about PrEP failure (“PrEP can fail for many more reasons than I thought.”) No, it can’t. The number of true PrEP failures remains tiny — especially compared to the frequency with which people contract HIV despite their best intention to use condoms.

    “In fact, PrEP resistant strains are circulating in my community.” Again, there is no proof of that. This whole scare is apparently based on a single self-reported case, without independent proof that the individual who seroconverted had been adherent.

    This is not 1982. While we certainly want to prevent HIV infections, they are not a tragedy of colossal proportions. Encouraging gay men to be terrified of each other, and reinforcing the prejudice that HIV is the worst possible horror, is not a rational or effective strategy for reducing risk. Fanning the flames of stigma and fear of people living with HIV frightens people away from getting tested (not to mention needlessly dividing the community and crushing countless spirits).

    Encouraging a wildly disproportionate fear of PrEP failure means that some people who are already on edge about trusting a new prevention modality will be frightened away from trying PrEP. Many of them are at high risk, and some of them will, needlessly, be infected.

    Apparently your intention in all of this is to enlighten people who falsely believe that PrEP is 100% efficacious. Fair enough — it’s probably somewhere between 99% and 99.9%. Do you also warn people that condoms are far from 100% foolproof? Do you mean to return us to the era of sheer terror about sex that gripped the community for years? What purpose does that serve?

  3. Dear John Doe,

    I applaud your strength and your love for your community – thank you so much for writing this letter and allowing your words to be made public. I am so sorry you are facing this, but hope that you have the support from your community that you need.

    My thanks and appreciation for your strength,

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