Pre-Exposure Prophylaxis or PrEP

Pre-exposure prophylaxis (PrEP) involves putting HIV negative people on antiretroviral drugs (ARV) with the aim of protecting them from HIV infection. This blog looks at some of the pros and cons of PrEP.

Tuesday, November 26, 2013

HIV Drug Regimes: the Good the Bad and the African

The reactionary (or 'mainstream', if you prefer) view of HIV transmission in African countries is that it is predominantly a result of 'unsafe' sexual behavior. Early interventions to reduce transmission included exhortations to 'abstain' from sex, to be 'faithful to one faithful partner' (or something like that) and to use condoms (an approach that later became known as ABC). Most people didn't know what words like 'abstain' and 'faithful' meant, but they became very good at repeating them until other interventions were dreamed up.

Like 'ABC', more recently touted interventions such as mass male circumcision and pre-exposure prophylaxis (or PrEP; the use of antiretroviral drugs by HIV negative people with the expectation of reducing the risk of infection), also depend on replacing some kind of 'unsafe' behavior with some other kind of behavior, deemed to be safe, or safer, or fervently hoped to be safer. Both circumcision and PrEP require that people also adhere to the strictures of the ABC approach (and if the name sounds paternalistic, that's exactly what it is).

Ever-paternalistic when writing about Africa, the BBC has heard that "some sex workers are having unprotected sex - and taking antiretroviral drugs afterwards to cut the infection risk". This is called post-exposure prophylaxis, or PEP. It has long been available in developed countries to people who are accidentally exposed to HIV, through their occupation, as a result of sexual assault, etc, although it is probably not as widely available in high HIV prevalence countries with inadequate health services, low levels of education and poor drug supply systems.

The BBC article is claiming that sex workers should be using condoms, but sex workers themselves are pointing out that they can make more money if they don't use condoms; clients are often willing to pay more. Most sex workers don't have the massive number of clients that media outlets such as the BBC have reported in the past, so they need to get as much money as they can each time they do get a client. The BBC is also 'concerned' that sex workers are using PEP too often; some say the drugs should only be used a maximum of once a year, otherwise they may cease to be effective.

In contrast, those touting PrEP can't speak highly enough of the use of drugs to reduce the risk of HIV transmission (as a look back through previous posts on this blog will show). Trials of such drugs are promoted in frequent press releases, perhaps in the hope of receiving the customary spontaneous standing ovation that some announcement must receive at every AIDS conference. The media generally picks up the press releases and spreads them far and wide, sometimes embellishing them with an extra layer of gilding.

PrEP and PEP are different. In general, PEP is taken after exposure. PrEP is taken before exposure by a person who faces a high risk of infection, or who is thought to face a high risk (which is just about every sexually active person in high HIV prevalence countries). But there are different versions of PrEP, daily and intermittent. The daily version involves taking the drug every day; but the intermittent version is taken just before sexual intercourse, or even just after.

Both versions require strict adherence to the regime, but it's clearly a lot easier to take a drug just before or just after a specific event than to take a drug every day because you or someone else considers you to face high risks of infection. Intermittent PrEP is still being studied, but the general tone of Big Pharma press releases about PrEP is that it is a great thing, that trials are doing very well, and that if people (and governments) will just pay their exorbitant prices, everything will be great. Strangely, the tone used about PEP is usually far more measured; perhaps PEP is just not lucrative enough as a market?

But the BBC can't resist the temptation to point (or at least wag) their finger. If people in African countries are infected, it's because of their behavior. If interventions don't work it's because of people's behavior. If drugs don't work it's because of lack of adherence. If people don't appear to be following instructions it's because they are failing to 'adhere to the regime'. If people are infected and know it wasn't because of their sexual behavior they are said to be 'under-reporting', or simply lying. Etc.

You get the picture. We are clever and they are not. Some people writing on the subject are even happy to use the word 'stupid', because the 'good AIDS/bad AIDS' dichotomy didn't disappear in the 1980s, as it should have. It lives on in the media, in popular books about AIDS and various other sources. There are also different drug regimes available for the good and the bad, those who were infected 'by accident' and those who are 'reckless'.


Sunday, November 17, 2013

Could PrEP be in Competition with Mass Male Circumcision Programs?

After years of trying to create a market for pre-exposure prophylaxis (PrEP) pills, such as Truvada, Big Pharma has turned to their favorite mass marketing ploy: dumping their products in African countries that are starved of health funding. Of course, why wouldn't they dump them in Africa, won't they be paid for with donor funding?

An article in Kenya's The Star entitled "Kenya: 'Wonder Pill' for Risky Sex On the Way" takes the unusual step of raising some difficult questions about PrEP, rather than repeating the Big Pharma press release, despite a shaky introduction. The article continues "Kenyans involved in risky sex behaviours will soon get a 'wonder pill' that can prevent HIV infections. Experts say Truvada, which some call the 'new condom', can reduce chances of catching HIV but there are fears the drug may be misused by the youth".

What, exactly, would constitute misuse of the drug? If it can cut the risk of infection by "up to 75 per cent if one faithfully swallows it daily", what could go wrong? Well, as the article eventually reveals, most people don't swallow drugs daily and most people can not expect 'up to 75%' reduction in risk. That figure is not even from a randomized controlled trial, but from a 'sub-group' study, where the best results are used to exaggerate the level of protection people, in (comparatively) strict trial conditions, may expect. Outside of that sub-group, and outside of drug trial conditions, risk reduction is far lower.

It's odd that such reports talk about studies and proofs for something that they then refer to as a 'wonder pill', a 'new condom' and talk of 'up to 75% protection' (although that's a bit weak compared to the term 'invisible condom' used by those marketing mass male circumcision), and the like. These are PR buzzwords, not scientific findings.

It is said that PrEP programs intend identifying those most at risk of being infected, such as sex workers, intravenous drug users and men who have sex with men. This will be a departure from vilifying these already stigmatized and criminalized groups; it remains to be seen how much donor funding will actually be spent on these groups to provide them with PrEP, given that it has been so difficult in the past to provide them with condoms, injecting equipment and even basic sex and sexuality education.

As the article says, Truvada is expensive, and it has made billions of dollars for Gilead. So it's worth their while pushing as much of the stuff as possible in countries with high HIV prevalence while the patent guarantees that their product will face little competition. By the time the patent expires the likes of Bills Clinton and Gates will surely have set up some program whereby the drugs can continue to be purchased at inflated prices.

The article makes the important point that nearly 1 million HIV positive Kenyans currently need antiroviral drugs just to keep them alive. So why would donors want to provide these same drugs to people who are not yet infected with HIV (aside from an obvious desire to enrich big pharma)?

Oddly enough, a cost effectiveness study makes its estimates using existing levels of male circumcision and antiretroviral therapy. This means that the three multi-billion dollar programs will be in direct competition with each other for funding, and each one will be trying to claim that any drop in HIV incidence is a result of their work. The study also seems to assume far higher levels of success than have been achieved so far. But that's big pharma for you.

While Gilead and other pharmaceuticals can gain a lot from any increase in antiretroviral therapy and PrEP programs, they may not stand to gain from mass male circumcision programs. Their assumption that their PrEP programs will be cost effective only in countries where circumcision levels are low suggests that by the time their product may be approved, the circumcision programs will already need to have failed, some time around 2015.

Worries that people may use PrEP as a kind of recreational drug, so they can dispense with the use of condoms when they are engaging in sex with people who may face a high risk of being HIV positive are not very convincingly addressed; nor are worries that overuse and misuse of antiretrovirals, either for HIV positive people or as PrEP, are brushed aside, with remarks about "government policy" and making the drug available "in form of a package that probably includes HIV testing and other prevention methods".

I seem to remember condoms, circumcision, ABC and various other programs being made available in the form of a package, without that leading to extraordinary results. But it will be interesting to see if PrEP will erode some of the funding currently being made available to, or earmarked for, mass male circumcision programs.

Circumcision programs stand to rake in billions for the big providers, but widespread use of PrEP would be worth far more. It's unlikely that a full scale version of both programs could co-exist; they are not mutually exclusive, but their cost effectiveness is predicated on their being the only or the main program in high HIV prevalence countries.

Whether one program displaces another, or whether they all get funded, the losers will be people in high HIV prevalence African countries, which will continue to suffer from under-funded health and education sectors. They will continue to be a mere 'territory' for sales reps, who will continue to carve things up in ways that should be very familiar to us by now.


Saturday, July 20, 2013

Treatment Action Group Raises Concerns About Thai PrEP Trial

The media reacted predictably when it was announced that a pre-exposure prophylaxis trial in Thailand showed some promise in reducing HIV transmission among intravenous drug users (IDU). However, many raised concerns throughout the course of the trial about how it was being conducted. One concern was that clean needles were not provided to trial participants, even though these are known to be the best means of reducing transmission among IDUs. But there were other serious issues that put a question mark over the value of the trial.

Another observation is that "the extent to which tenofovir protected against parenteral versus sexual exposure is unknown". The extent to which sexual versus parenteral exposure may have been involved was never questioned in many other PrEP trials, in mass male circumcision trials and in trials of numerous other HIV prevention interventions. Many HIV related trials fail to account adequately for modes of transmission, assuming that the virus is almost always transmitted sexually, often despite evidence to the contrary.

I'm just curious to know why these concerns have been raised by the Treatment Action Group about this trial in particular, when serious concerns about some other HIV prevention trials don't seem to be heard much, at least, not without attracting accusations of 'denialism' and similar ad hominem responses.