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.

Wednesday, July 27, 2011

Wagging Fingers Hasn't Worked; Let's Try Pills

It is very reassuring that a commentator in Kenya has mentioned, albeit briefly, that providing ARVs to HIV negative people will strain resources in a country where it is not even possible to supply all HIV positve people with them.

Many people don't have food, water, cheap drugs for everyday, but deadly, diseases, contraception and family planning, proper education, infrastructure, and a great many other things. Why the obsession with grossly overpriced drugs that will not make any material differenc to most people's health?

But there are some odd remarks in the article. One person mentioned in the article that she had not had sex with her husband for the first three years after finding out that he was HIV positive. Then she started to use condoms.

So far so good. Condoms give a good level of protection if they are used properly and used all the time. There are all sorts of stories about condoms breaking but this should be rare if people really know how to use them properly. And at least condoms are cheap and have other benefits, protecting against sexually transmitted infections and preventing unplanned pregnancies.

But the article is about using drugs to reduce HIV transmission. This would be in the form of pre-exposure prophylaxis (PrEP), where a HIV negative person takes an antiretroviral drug regularly to reduce the probability of being infected, or 'treatment as prevention', where the HIV positive person takes ARVs which reduce the viral load to a level where HIV is a lot less likely to be transmitted.

If condoms are used, is the risk that the HIV negative partner faces going to be reduced further when they also take PrEP? Perhaps so, perhaps a belt and braces policy gives more protection.

But if the HIV positive partner is on ARVs, taking them correctly, responding to them (to the extent that their viral load is low, etc), does the HIV negative partner need to be taking PrEP? Couldn't the HIV negative partner just make sure that condoms are used?

The more important questions are about whether there will be enough money for all HIV positive people to receive the drugs and other care they need, as well as for HIV negative people to receive the most effective prevention assistance available.

Currently, only 20-40% of people in need of ARVs are receiving them. Will the need for PrEP be given priority over the need for ARVs, given that PrEP is for people who are healthy and normal ARV treatment is for people who are sick and will die without the drugs?

But even 'treatment as prevention' is not that straightforward. The majority of people in most African countries do not know their HIV status. Even the majority of HIV positive people do not know their status. How easy will it be to identify all HIV positive people and keep on identifying new infections for as long as they occur.

Apparently Swaziland is going to test its entire population and put everyone found to be HIV positive on ARVs, effectively, 'treatment as prevention' or 'test and treat'. There are only 1.2 million Swazis but an estimated 200,000 of them are HIV positive.

Yet only about 60,000 HIV positive Swazis are on ARVs and the country doesn't even have enough supplies for them. Similar shortages have occurred in other African countries. Health services can barely cope with keeping a fraction of people on treatment, let alone all those who need them.

The Kenyan article continues with the sort of honesty that you wouldn't normally find in an article about HIV: prevention so far has had little impact and the rate of new infections is still very high; sexual behavior change, the main aim of most prevention programs, has not occurred to any great extent.

But UNAIDS and the HIV orthodoxy have, according to the article, been targeting the wrong people all along. They have been talking about reducing numbers of partners, using condoms and even giving up sex altogether. But many new infections occur in mutually monogamous couples, often among people who take precautions and who don't take risks.

The biggest problem with both PrEP and 'treatment as prevention' is that we have been very poor at identifying where new infections are coming from, so we are still, many years and billions of dollars later, in a poor position to know how to traget these expensive interventions, if the money does miraculously appear.

HIV prevention programs are usually targeted at whole populations, many of whom are not at risk. But even those who are not 'at risk' by UNAIDS' criteria become infected with alarming frequency. The plan seems to be to put as many people as possible, HIV positive and HIV negative, on drugs because, rather than despite the fact that, we haven't a clue why most people are infected.

ARVs appear to have an effect, whether used for PrEP or 'treatment as prevention', but we don't really know who to give them to. So we are going to try and give them to as many people as possible, in the hope that it will work, apparently. Is this modern medicine? It's no wonder people are suspicious about 'public health' programs.


Wednesday, July 20, 2011

ARV Resistance: the Ultimate Pharmaceutical Industry Wet Dream

Few in the pharmaceutical industry wish to discuss the important issue of resistance developing to antiretroviral drugs (ARV). Resistance inevitably develops but the question is, at what rate? In high prevalence countries, which are also resource poor countries, there are very few types of ARV available. So when resistance develops to the common ones, there are few alternatives left and most of them are prohibitively expensive.

Ed Susman discusses resistance, which seems to develop rapidly in the US. The US has one of the highest average spends on healthcare in the world. People on ARVs there are monitored carefully and their regime is changed relatively quickly when the patient is not responding for any reason. This is unlikely to happen in developing countries, where most detailed monitoring is beyond their reach, for a variety of reasons.

Another thing Susman discusses is transmitted resistance, which means that a person with a resistant strain of HIV can transmit their resistance, along with the virus. Therefore the current rate of resistance could rise sharply, especially where HIV transmission rates are high.

This might be an acute problem in countries where there is talk of rolling out PrEP on a large scale or using HIV treatment as a means of preventing HIV transmission. Huge numbers of people will be on ARVs with very little monitoring and probably fairly lax adherence. Given that it takes many months to discover non-response to drugs and provide a change of regime in some rich countries, this problem is going to be a lot more challenging in poor countries.

Susman does not discuss resistance in a context where some, perhaps a lot, of HIV is transmitted non-sexually. If large numbers of people are being treated in unsterile conditions and HIV happens to be transmitted nosocomially, the rate of resistance to common drugs, usually the only affordable ones, could increase and leave many patients beyond help.

As one of Susman's informants says "individuals infected with HIV who respond to antiretroviral regimens can anticipate a life expectancy that is similar to uninfected people, because of the number of treatment options currently available. However, in these young people who already have lost one or two or more classes of drugs, [there will be] limited options for therapy". The options will be a lot more limited in African countries, if there are any options.


Saturday, July 16, 2011

Pharmaceutical Industry Front Group Blows its Own Trumpet

Pharmaceutical industry front group AVAC is blowing the usual trumpet for PrEP because some recent trial results have been encouraging. They said predictably little about results which were not so encouraging.

The problem with PrEP still remains: no high prevalence country has managed to put all HIV positive people on antiretrovirals, not even all those who are at the stage of disease progression where it is a serious threat to their health. Why does anyone think they can roll out a drug for people who are not infected with HIV on the grounds that it might give them 'up to' 73% protection?

If 20% of sexually active people are infected with HIV and most of the other 80% are considered to be at risk of infection, will they all be given PrEP? Think of the cost, the logistics, the high levels of resistance, the side effects, things instititutions like AVAC and UNAIDS don't seem to be willing to discuss sensibly.

It also seems like a humiliating climbdown for UNAIDS and all the others who maintained that HIV is almost always spread through unsafe heterosexual sex in African countries (though hardly ever in non-African countries, however unintuitive that may sound). Are all 'risk reduction' strategies now to cease?

Will we instead just give out drugs and ignore the things we appeared to deplore for the last thirty years, promiscuous men, survival sex, commercial sex work, exploitation, early and unplanned pregnancies, early marriage, concurrent relationships, large numbers of partners, low use of condoms, lack of family planning and whatever other issues we have spent so long bemoaning?

Warren Mitchell from AVAC remembered to thank the trial volunteers, presumably mostly guinea pigs who, if they are African, will never be able to afford the drugs and for whom the money to pay for them may never be raised. I don't suppose he was being ironic, either.

Another move which looks suspiciously like a way to vastly increase the volume of ARV drug sales, and thereby increase dependency on drugs and funding, is a strategy called test and treat (or various other names). This involves testing the whole population of a country regularly, perhaps every year, and putting everyone found positive on treatment.

Testing even a reasonable percentage of people in a population once has remained elusive, let alone the whole population or the whole population every year. But even testing once a year is not thought to be enough, so test and treat is still just a theory. And it is well known that early treatment carries a lot of risks that have not yet been adequately explored.

It is to be wondered if people will be obliged to take the drugs by law or if they will face stigma if they refuse. UNAIDS has many years of experience in the use of stigma as a weapon with which to threaten people and punish them for being African so perhaps they have some plans in this area. No disease has ever been beaten by drugs alone so it seems hard to believe that HIV will be the first. But it is great news for the pharmaceutical industry.

[For more about PrEP and HIV issues in Africa, see my other blog, HIV in Kenya.]