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Aug 5, 2018

Hi Damon, thanks so much for your reply to my previous email it has been extremely helpful. After reading your answers though I have three other small doubts: * you mention If your partner is using PrEP as prescribed, then he would still have the full protection afforded from using PrEP even if you were HIV positive, not in treatment, with a resistant strain, with a detectable viral load. PrEP protects the person who is using it from HIV. That includes resistant detectable strains of HIV. but this does not apply if these strains are resistant to Truvada, correct? And I also assume from what you are saying that the strain I could develop, might not be resistant to Truvada, right? Am I getting you wrong? * you write "In other words, it is EXTREMELY likely that you would acquire HIV while on PrEP" but only in case I meet an HIV resistant strain to Truvada, isn't it? * how long does it take for HIV strain to get resistant to Truvada? This does not happen from day to night, does it? As you can understand from these questions I'm a new PrEP user, maybe a tiny bit paranoid about this whole new situation to me and yet taking it because I believe in this tool. So once again thanks very much for your patience and time in answering my questions Kind regards

Response from Mr. Jacobs

Hi there -- Thank you for the follow up questions! [People can read the original post here:]

So I think your concerns are rooted in a question that has come up for many people taking PrEP, as well as for providers prescribing PrEP. That concern is: If someone on PrEP has the maximal protection from taking the drug daily, would they be protected if they were exposed to a strain of HIV that was resistant to the medications in PrEP?

The truth is, we simply don't have accurate data to sufficiently answer that question. We know there is one human being who acquired a resistant strain of HIV while taking PrEP daily in Canada in 2015. When that happened, I anticipated that we would see more cases in Canada and other parts of the world. I thought we might see clusters of new resistant strains of HIV being passed around in certain communities.

But that didn't happen. So while we know that one person acquired a resistant strain while adhering to PrEP, we don't know how many people on PrEP have been exposed to the same or similar strains without becoming HIV positive. We don't have any additional reports of this happening. As of now, we only know of two people who have acquired HIV with documented adherence to PrEP. The second person did not acquire a strain of HIV that was resistant to HIV medications (

In other words, we know there are people out there who are living with HIV, have a detectable viral load, and have a strain of HIV resistant to the medications in Truvada. We know that some of these folks are fucking people who are HIV negative and using PrEP as prescribed. These folks are not acquiring HIV from these encounters. So why does it not happen for them, but it did happen for one person in 2015? We simply don't have medical information to satisfactorily answer that question.

As you note, the other concerns about resistance is if someone who is HIV positive and doesn't know it, takes Truvada or its generic equivalent, thinking they are taking it to prevent HIV when they already have HIV. In those cases, their virus can indeed build a resistance to the medications in Truvada. How long does that take to happen? No one knows for sure. But I do know that providers who are concerned about this will take extra precautions by testing their new PrEP patients for HIV every 30 days instead of every 90 days (per medical regulations). If new HIV transmissions are detected early enough, they have not led to resistant strains. The resistant strains we've seen appearing PrEP patients have occurred when that person (1) acquired HIV while not taking PrEP and (2) wasn't regularly being monitored by a provider.

So although there are some variables we don't know, there is a lot we do know: (1) Taking PrEP as prescribed reduces risk of acquiring HIV, even from resistant strains, by more than 99%, and (2) Regular HIV testing while using PrEP, especially in the beginning, can help avoid developing resistant strains in people who are already living with HIV and don't know it.

For more information, resources, and support, feel free to join the conversation over in the Facebook PrEP Facts group page at:

First time unprotected sex
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