Truvada and Asymmetric Information

Let us be thankful today for the public and private sector scientists who developed and tested Truvada, which seems to have significant power to prevent HIV infection (Good interview with Tony Fauci here).

Safe sex decisions depend in part on knowledge of one’s sexual partner’s HIV status. About 1 in 5 HIV positive people don’t know that they are positive, and even those that know do not always disclose this information. A preventive pill surmounts these problems, allowing the person who takes it to know they have some degree of protection even in the face of the imperfect risk information that is an inherent part of sexual contacts.

Author: Keith Humphreys

Keith Humphreys is the Esther Ting Memorial Professor of Psychiatry at Stanford University and an Honorary Professor of Psychiatry at Kings College Lonon. His research, teaching and writing have focused on addictive disorders, self-help organizations (e.g., breast cancer support groups, Alcoholics Anonymous), evaluation research methods, and public policy related to health care, mental illness, veterans, drugs, crime and correctional systems. Professor Humphreys' over 300 scholarly articles, monographs and books have been cited over ten thousand times by scientific colleagues. He is a regular contributor to Washington Post and has also written for the New York Times, Wall Street Journal, Washington Monthly, San Francisco Chronicle, The Guardian (UK), The Telegraph (UK), Times Higher Education (UK), Crossbow (UK) and other media outlets.

9 thoughts on “Truvada and Asymmetric Information”

  1. Aside from questions about the advisability of chronic administration of a powerful medicine to people, who have no disease, I wonder whether substituting a pill you'd like to think you took faithfully, for a condom, is going to be a good option. I'm not saying that a program of public propaganda regarding how this pill is used couldn't tip the balance of behavior and outcomes in a desirable direction, but I the dollars behind the pill vs. the dollars behind the condoms, when combined with other realities of human nature, give me some pause. I'd give one cheer, not three, at this early stage; holding my breath on the other two cheers.

  2. Here's an interesting test: culture warriors opposed the HPV vaccine and the morning-after pill on the grounds that they would reduce the costs that girls and young women would bear for having sex. Will they now oppose Truvada on the same grounds? Or are they only concerned with stifling female sexuality?

  3. I think these findings need to be taken very cautiously. This is one study and it comes connected with a great deal of speculation. For example if people think that they are protected by taking this drug, will they engage in greater risk taking behavior? Will people stop using condoms? They shouldn't based on this finding! Will enough truvada become available to enough people to make a difference? Will it only be available in developed countries? Still it is a very welcome finding and if it can be scaled up in a meaningful way it shows real promise. Of course it took us 20 years to overcome the ban on syringe exchange (another proven effective means of prevention) so I am not ready for a victory lap.

  4. Caphilldcne: I agree with you that in the real world, some people who are not being closely monitored and supported as they were in the trial may engage in less safe sex behavior because they are taking the Truvada pill. This could lead to the trial overestimating the preventive benefit of the medication. However, as an ethical clinical trial this study did not employ a "no treatment control". The control subjects got "HIV testing, risk-reduction counseling, condoms, and management of sexually transmitted infections". What this means is that to show a benefit, Truvada had to get over a much higher bar than it would have in the real world (especially the developing world) where most people get absolutely nothing in the way of services. This would lead to the study UNDERestimating real world benefit, and quite possibly by a large margin.

    Also, in a world where many people believe all opinions are equal, I hold to the view that there is such a thing as an expert, and three of the sharpest, most knowledgeable, most honorable AIDS scientists in this country — Drs. Jono Mermin, Tony Fauci and Kevin Fenton — have been in the media saying this is a major advance. Good enough for me.

  5. I'm not saying it's not a major advance. I'm saying that scale-up and follow up should be extremely cautious and that this is far from a magic bullet. Also, I think Jono and Kevin at least would concur with that assessment. Considering we live in a country that took 20 years for the federal government to agree to pay for syringe exchange, I really question whether this is going to be an especially easy task for prevention.

  6. Caphilldcne: There are almost no magic bullets when it comes to diseases that have a behavioral component, I take that as a given and wouldn't dispute you on that. But I think it's okay to be happy, even excited about this finding, particularly after a lot of failed biological AIDS prevention and treatment interventions which I assume you know about. And as I assume you also know, the AIDS field really needed a breakthrough to renew optimism, urgency and public attention, and this is wonderful in those respects….there will be room and time for cautions, setbacks, struggle, disappointment etc., but I chose at this moment to feel unreservedly happy in part because so much of the AIDS picture has been disappointing recently and every field needs some moments to celebrate.

  7. I am really wary about celebrating. Sorry. I've been far too disappointed over the years. I hope I'm wrong and there is a way to scale this up and refine it (and we need more than one study).

    Which reminds me to say, Randy Allgaier, RIP. I can celebrate Randy, what a good, good man he was.

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