I recently read about a man who was on PrEP in Amsterdam, and though he appeared to be taking it daily still contracted HIV. Furthermore, the strain of virus he contracted does not seem to be drug resistant. This was back in February and it seemed researchers were puzzled how this could have happened. Do you know of any new information that explains this scenario?
As you read, we now know of a second instance in which an individual who had verified adherence to PrEP acquired HIV despite their consistent usage. And, this is the first time ever that we are able to see what happens if a person uses PrEP consistently and acquires a strain of HIV that is NOT resistant to tenofovir and emtricitabine, the medicines in Truvada.
Since this information was released back in February, 2017, not much else has been learned or reported. The case study followed a 50-year-old cisgender gay man who became HIV positive eight months after starting PrEP. He was in a research trial in Amsterdam, and therefore there was excellent documentation of his consistent adherence to PrEP. The patient tested negative for HIV at the start of PrEP, and again at one month, three months and six months before he tested positive.
The patient reported an average of about 50 anal sex partners per month before diagnosis. He also reported having condomless anal sex on about 50% of the days before diagnosis. The median number of sex partners per day with condomless anal sex ranged between two to five each month. Additionally, the patient experienced two instances of rectal gonorrhea and one instance of rectal Chlamydia. He also reported using drugs during sex, including amphetamine, cocaine, mephedrone and ketamine. (http://www.thebodypro.com/content/79379/hiv-transmission-despite-adherence-to-prep-and-no-.html).
So what does this mean, and what does this explain? Unfortunately, not a whole heck of a lot. Although the quantity of sexual partners, drug use, and concurrent instances of having STIs may have contributed to PrEP's failure here, the researchers can not be certain of that. There are at least 200,000 people in the world using Truvada for PrEP and I am sure that some of them are having just as many sexual partners, drug experiences, and STIs, without acquiring HIV. Nevertheless, this is the only case known or reported where a strain of HIV that is resistant to Truvada did not "break through."
Dr. Elske Hoornenborg, an infectious disease specialist at Public Health Service Amsterdam who supervised this case, offered her own perspective on some of these mysteries and hypotheses brought up by this case: http://www.aidsmap.com/Unique-case-of-PrEP-failure-without-drug-resistance-reported-from-Amsterdam/page/3119879/. But given this was an isolated case that hasn't been similarly reported or documented anywhere else, for now we just have to say it was an anomaly and hope that in the future we will understand more.
I know when something like this happens we hope there are lessons to be learned. As a PrEP consumer myself, I know I look at this case and think, "Is there something here that can help me understand how to use PrEP without getting HIV?" But given the sparse data, and the unique conditions of this case, there just doesn't seem to be that data.
As I said earlier, we do know that there are at least 200,000 consumers of PrEP globally (it's impossible to ascertain a more exact number, but that is on the conservative end of the estimate). And of these 200,000+ consumers, there are only two documented instances where someone acquired HIV with verified adherence since 2007. If PrEP was only 99% effective, we would expect to have seen about 2000 people acquire HIV while using PrEP.
So although we don't have clear answers forthcoming from the Amsterdam case, I think we can gain insights from these stats. Yes, there have been outliers, and I have no doubts there will be more in the future. But are these likely outcomes? Not really. We are literally more likely to be struck by lightning (about 24,000 lightning deaths per year) than acquire HIV while using PrEP (https://www.theguardian.com/world/2014/jul/28/venice-beach-lightning-death-15th-this-year).
For more information about PrEP, research, updates, and experiences, please visit the global Facebook "PrEP Facts" group at https://www.facebook.com/groups/PrEPFacts/