Posted on February 23rd, 2011 No comments
Pre-exposure prophylaxis – called PrEP, is an HIV prevention intervention where antiviral drugs are taken by HIV uninfected individuals in the hope that sexual transmission of HIV will be prevented. A recent trial of daily Truvada, a combination of two anti-HIV drugs demonstrated only a 44% reduction in the risk of becoming HIV infected by sexual transmission among men who have sex with men (MSM). I have written about this trial a few months ago.
Unbelievably, the use of this intervention has in effect been endorsed by the US Centers for Disease Control (CDC). True, the CDC call their recommendations on the use of daily Truvada as PrEP an “interim guidance”. But anything short of “don’t risk your life by taking an intervention that cannot even halve the chance of becoming HIV infected” is in effect an endorsement. Simon Collery has also written about this calling the CDCs recommendations a “mixed message”.
The CDC is not alone in regarding an intervention that is only 44% effective in preventing a potentially lethal infection to be good enough to be implemented. Quite surprisingly some groups claiming to represent the interests of those at risk share this bizarre view. One implication is that these groups, supposedly representing people at risk for sexually transmitted HIV, as well as the CDC have given up on persuading MSM to use a condom, as described by Michael Weinstein in a recent article .
In reality groups calling for an implementation of an insufficiently effective intervention to prevent a life threatening infection may be a small minority whose real influence is probably insignificant in relation to their noisy irrational advocacy.
People on the ground, dealing with risk are often wiser than those who claim to advocate on their behalf, but do not have the means to influence the way issues are reported in the media. They know that a 44% efficacy in reducing the chance of acquiring a life threatening infection is just not good enough. They know that condoms are the most effective way to prevent sexual transmission of HIV.
But when this insufficiently effective measure was first announced in November of 2010, it was hailed as a triumph. Time magazine even called this ineffective intervention the most significant medical breakthrough of 2010! I suspect these accolades may have resulted from the skill of publicists rather than of independent investigative reporting.
But of course I may be part of a minority in considering that a trial demonstrating that an intervention that is only 44% effective in preventing a potentially lethal infection is far from a triumph and rather is an emphatic failure because a much more effective protective measure is readily available that’s cheaper and safer.
Concerns that condoms may not be used regularly in appropriate situations to prevent the sexual transmission of HIV are better expressed by a support for extended properly targeted prevention education.
PrEP trials began in the early 2000s and have had a troubled history. Trials were planned and even several started in African countries and in Thailand and Cambodia. Some never got off the ground, and several were stopped for a variety of reasons. There were vigorous activist demonstrations in connection with some. The varied concerns of activists included provision of care to trial participants who became infected, or the provision of sterile injection equipment to IV drug users in Thailand.
I posted a blog on the POZ magazine website in August 2009 describing an ethical problem with PrEP trials, essentially that PrEP would have to be tested with an imperative to provide and encourage the use of effective means already available to prevent HIV transmission, namely condoms and sterile needles. If these measures are conscientiously provided and their use encouraged it’s unlikely that any effect solely attributable to PrEP could be measured. iPrEx told us that self-reported adherence to medication is unreliable, so there is no reason to believe that self-reported frequency of unprotected sexual intercourse is any less so.
In that post there are links to two significant articles published in 2005. The first represents the view sympathetic to those who demonstrated against PrEP trials. It can be seen by following this link:
The second is the view of PrEP researchers.
One of the ways suggested to forestall the problems that have beset so many PrEP trials in the past was to solicit a greater degree of community involvement early in the process with a view to obtaining their commitment.
An effort was made to obtain community support for PrEP trials with the help of UNAIDS. There have been many teleconferences and many publications about PrEP best seen by looking at this website. http://www.avac.org/
It’s evident that much effort and expense has been placed into engaging communities in the design and conduct of PrEP trials. Apparently with some success as I believe the earlier upheavals associated with PrEP trials have not been repeated.
As for as expenditure on PrEP trials and PrEP promotion, the following figure indicate funding amounts and sources.
Despite this expenditure, it’s most unlikely that PrEP with Truvada will be used by more than a very small minority of individuals.
Apart from the cost of the medication, it will be necessary to pay for regular tests for HIV infection and for monitoring for drug toxicity. It’s likely that some of those who choose to use Truvada as PrEP will forgo these regularly needed tests, because of cost and other reasons. Not only are these individuals risking infection with an insufficiently effective preventative measure, they also risk the development of virus resistant to the antiviral drugs in Truvada because of receiving a suboptimal dose during an unidentified infection.
With only a 44% reduction in the risk of becoming HIV infected, unidentified infections are a very real possibility among individuals who choose to use daily Truvada as PrEP. It’s realistic to be concerned that some of these individuals will not be tested regularly to detect infection. Individuals with an undetected infection could then pose a risk to their uninfected sexual partners. Who knows how suboptimal treatment will influence the course of initial HIV infection?. Even the illness of primary infection that could be an alert, may be less likely to occur. Failure to be tested regularly would also mean that drug toxicity, specially to the kidneys is less likely to be detected.
With all these hazards, not only to the individual using PrEP, and with the likelihood that Truvada, and indeed other antiviral medications can be obtained without a prescription, the CDC’s interim guidance is unwise. It’s also unfortunate that there may be some who will see additional significance in that the guidance is specifically directed at “high risk” MSM.
Properly targeted prevention education with the promotion of, and support for condom use needs all the support it can receive.
Daily Truvada as PrEP is a really bad idea.