2010 will be a year to remember for the field of HIV prevention. After decades of interventions with limited results (with the exception of circumcision and the prevention of mother to child HIV transmission), two clinical studies are raising the hope that the HIV epidemic can be tamed.
In July, the CAPRISA team (based in South Africa) reported that a vaginal gel containing the anti HIV drug tenofovir could reduce the risk of HIV infection by 39%. This was the first proof of concept that a microbicide could potentially reduce the risk of HIV infection whilst offering women an HIV prevention tool that they could control.
In November of the same year, the iPrEx study conducted on a population at high-risk of infection showed that taking the anti HIV Drug Truvada reduced the risk of contracting the virus by an average of 44 percent.
Both studies are hailed as a milestone and landmark in the history of HIV prevention and expectations are high that HIV prevention will finally mean more than the ABC of ‘Abstinence, condom and faithfulness’. But despite the hope, neither approach will immediately translate into marketable products as there are a number of questions that needs answering before microbicide and PrEP are available to the public.
Can a pill a day prevent HIV?
The iPrEx study was a large clinical trial, sponsored by the US-National Institutes of Health (NIH) with co-funding from the Bill and Melinda Gates Foundation and drugs donated by Gilead Sciences. Its purpose was to test if taking two anti-HIV drugs on a daily basis could help prevent HIV infection amongst HIV negative people at high risk. The approach called Pre-Exposure Prophylaxis (PrEP) is based on the concept that drugs are taken to prevent infection rather than treat it. This is similar to taking anti-malarial tablets when travelling in areas where the disease is endemic. The study was conducted in the USA, South Africa, Ecuador, Peru, Brazil and Thailand and involved 2,499 sexually active Men who have Sex with Men (MSM). The drug tested, Truvada (a cocktail of two drugs), is commonly used to treat people infected with HIV.
The study, published in the New England Journal of Medicine, showed 44% less HIV infections in the group that was given the drug compared to the group that received a placebo. These results represent a significant development in the field of HIV prevention. However, they cannot easily be translated to other groups ‘at risk’ or to the general population without further studies.
Whilst the PrEP approach raises hope for the prevention of HIV infection, it also presents a number of challenges for scientist, advocates, and crucially for public health systems. Many of these challenges, such as adherence (people taking their pill as prescribed), side effects, potential resistance (existing drugs becoming ineffective against the HIV), and cost effectiveness are best left for discussion by scientists and clinicians as they will require many more clinical studies.
In the meantime, the PrEP approach raises more pressing ethical and social concerns for public health.
PrEP can only be used by people who know they are not infected with HIV. Hence, those who want to access PrEP need to take an HIV test, not once, but at regular intervals. How often is not known yet, but every 3 or 6 months seems reasonable. Getting people to test once is not always easy for a number of reasons. Getting people to test regularly will be even more difficult (and costly), but not impossible if testing becomes part of routine health checks (a controversial issue in itself).
However, regular testing will lead to the identification of existing infections that in turn will require immediate treatment (in the US and the UK about half of those testing positive for HIV need to start treatment at the time of the diagnosis). As PrEP is rolled out, more people in need of ARV will be identified, and inevitably there will be a competition for resources between the sick and the healthy.
Providing ARV treatment to those who need it is already putting a huge strain on the health system of many countries in both the developing and developed world. Considering that only a third of those in need of treatment are currently receiving it under the new WHO guideline, prioritizing a potential PrEP roll out would be an inevitable necessity.
Could PrEP potentially be a useful option in some circumstances for some people, particularly for those populations called most at risk populations (MARPs)?
MARP is a broad acronym including Men who have Sex with Men (MSM), Sex workers (males and female, commercial or not), injecting drug Users (IDUs), and any population that has more risks of being infected by HIV than the general population. However, the concept of population ‘at risk’ or ‘vulnerable’ is a controversial and contested one. Not all MSM are ‘at-risk’, a large number of them actually use condoms regularly and consistently. Studies have even shown that gay men were often infected by their partner with whom they were in a stable relationship. Likewise, condom use amongst commercial sex workers can be high (for example it is over 90% in brothel-based sex workers in Cambodia), with many patrons using condoms with a sex worker but not with their regular sex partner. Hence it is not ‘Populations’ that need to be identified and reached, but individuals within these populations and this will be a serious problem if PrEP is prioritized.
Besides, the general population cannot be ignored, particularly in Sub Saharan Africa, home of 68% of all people living with HIV. The UNAIDS 2010 AIDS epidemic update observed that data from urban Zambia “suggest that 60% of the people newly infected through heterosexual transmission are infected within marriage or cohabitation , compared with more than half in Swaziland, 35%–62% in Lesotho and an estimated 44% in Kenya”. . A similar proportion of new infections occur among steady, long-term heterosexual partners all over sub-Saharan Africa suggesting that heterosexual and in particular young girls aged 19-24 could be the primary target for PrEP if it has to be prioritised to the most at risk.
In the current context where for every 2 people put on treatment, 5 become infected, suggesting putting millions of healthy people on treatment, some of them potentially at an early age, when so many who are in need of it can’t access it, is surely asking for trouble.
Taking a pill a day to avoid taking a pill a day?
Should PrEP be proposed to at-risk individuals as an HIV prevention option alongside other non medical approaches? There are still a number of clinical studies to conduct before PrEP is made available to the public. But in some cases PrEP could be detrimental to its intended recipients. For sex workers, the introduction of PrEP could mean replacing a highly effective HIV prevention method (condom) by a less effective one. PrEP is also expensive and will not protect against other STIs. It does not have contraceptive property and could put sex workers back under the control of customers who will be able to enforce sex without condom. For IDU, it would be replacing a non-medical approach that we know works: needles-exchange programmes. And when the acceptability of treatment for those sick with HIV is an issue, will healthy individuals even if at risk be willing to take a pill regularly?
Remarkably, most of those who are at higher risk of being infected with HIV are also those that governments are less prepared or likely to invest resources in. Health care for junkies, prostitutes and gay men rarely score high on the political agenda, and electoral pledges centred on the health of these groups wouldn’t attract many of the electorate.
It would be dangerous to ignore or disregard the impact PrEP could have on a national health system with the risk of introducing two tier/two waiting rooms health care. There will be those who can afford PrEP whilst others will still be on waiting list to receive anti-HIV medication (many already are, even in a developed country). The emergence of a black market in anti-retroviral drugs (ARV) and the spectre of counterfeits flooding it, should not be disregarded, particularly in the developing world where the most vulnerable could easily fell prey to ‘ARV drug dealers’.
To date, having failed to achieve the sustained change in behaviour required to reduce the number of new HIV infections at the population level, making little progress in getting rid of discriminative laws that stigmatise and cast out those most vulnerable (76 countries have state-sponsored homophobic laws), and facing the challenge of achieving universal access to HIV treatment by 2015 (MDG 6) should we now embark on this controversial approach to HIV Prevention?
The iPrEx Team deserves praise for the quality of their work and should be commended for providing the first proof that daily oral use of an anti-HIV drug can reduce the risk of HIV infection This is an important breakthrough for HIV prevention. It has been a long road pockmarked with ambushes and difficulties. But now, Pandora’s Box is open at a time when his holiness Benedict XVI is opening even ever so slightly the door to condom use, at a time when the World Health Report 2010 confirms that one billion people cannot afford healthcare and at a time when the latest UNAIDS AIDS 2010 epidemic update shows that the rate of new HIV infection is stabilising at around 2.6 million new infections a year.
No matter how one looks at it, the iPrEx study has opened the door to the medicalisation of sex, and in the current state of research and prevention, that amounts to taking a pill a day to avoid having to take a pill a day.
The views expressed in this article are the author’s and do not necessarily reflect the views of his employer or of the organisations he works for.
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