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Comment by aussieguy1234 | Hacker News Reader

There is already prep, a once a day pill that if taken consistently, is over 95% effective at stopping HIV infection, I've heard some sources say it's 100% effective. While it's not medically considered to be a vaccine, most vaccines for other conditions have a lower effectiveness rate.

There is work being done to turn prep into an injectable chip in the arm, like long term contraceptives, but for HIV prevention.

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The thing that worries me about antiretroviral drugs is that they mess with mechanisms that are innate to the reproduction of cells.

Their effects can, e.g., be clearly seen in changes to the bone marrow, which IIRC has some of the fastest-reproducing cells in the human body.

We don't have long-term data yet on what this does to users of this drug.

My wife has to take such drugs as she has HIV, and I wouldn't be surprised if it ended up shaving a few years off her life expectancy. She's fine now, but who can predict the cumulative effects? Of course, since without the drugs her life expectancy would be drastically lower, she obviously takes them, and they are a godsend.

But I'm kinda waiting for the other shoe to drop.

What I'm saying is: it's great that we have this option, and it should be used where it makes sense. However don't think that this medication frees you from worry in the same way vaccinations typically do. The tradeoff is much different.

It's true that there are definitely some side-effects and we'll need to wait and see what the long-term consequences are. The good news is that they at least appear to be well-tolerated drugs, and newer drugs show fewer adverse effects - minor bone-density reduction and renal function impact are the main adverse effects of Tenofovir + Emtricitabine, with no obvious effect on bone marrow for example.

But it's quite a tricky decision to make. Vaccines aren't without risk either, though adverse reactions are also rare. Certainly from a cost perspective, PReP with high efficiency makes a lot of sense – lifetime treatment and monitoring of an HIV+ patient can be markedly more expensive than a relatively cheap preventative medication, especially in high-risk groups.

I have been beating around the idea of taking PReP for a while, what with being part of a higher-risk group in an area with relatively high HIV prevalence. It's definitely a harder commitment to make than vaccination is, but I hope that we can improve our knowledge and understanding of the risks as the trials currently underway progress.

Can you point us to a source regarding this pill? Is it in clinical trials?

You must be North American, it has been in broad use for years: https://www.cdc.gov/hiv/basics/prep.html

This is a medication that’s far beyond the clinical trial phase and is widely available in many countries, though still subject to some large-scale trials for this particular usage. There’s lots of information on sites like https://www.iwantprepnow.co.uk - it’s available through the healthcare system in some parts of the UK, purchasable privately in others, and from what I understand available on some insurances in the US.

It’s a combination of two antiretroviral drugs also used in HIV treatment (Tenofovir and Emtricitabine) and the effectiveness of it can’t really be overstated - my understanding is that there are only two documented cases of someone correctly using this drug becoming HIV-positive, and in both cases due to rare strains with resistance to both drugs.

It’s not a vaccine, but it does change the picture massively for at-risk groups.

> and in both cases due to rare strains with resistance to both drugs.

So then it is only a matter of time before we have 'super' HIV strains that are resistant running around. Perhaps it's not such a great idea to have large numbers of people exposing these drugs to the virus regularly, else we'll end up with more resistant strains..

I'm not a virologist, but my understanding is that the lifecycle of HIV makes that unlikely. An individual must be infected with the virus in order for drug resistance to emerge; using PReP prevents infection from happening in the first place by stopping viral replication. HIV is quite hard to transmit – someone who is not infected or who is on a stable treatment regime can't transmit the virus to anybody, so resistance isn't much of a concern there.

The bigger risk of drug-resistant strains emerging is due to poor adherence to medication regimes. Missing doses of antiretroviral therapy can cause drug resistance to emerge rapidly, as viral replication is no longer suppressed and HIV mutates like crazy.

So what are you suggesting exactly, an end to vaccines? What makes HIV any different?

That is not a vaccine... No antibodies are created by the body to attack HIV. There's a big difference.

In the US it is marketed as Truvada (https://www.truvada.com/) which is the combination of drugs used. Approved by FDA in 2004.

PrEP sold under the name Truvada in the U.S. I actually saw a TV commercial for it earlier today.

https://www.cdc.gov/hiv/basics/prep.html

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