PrEP is an HIV prevention intervention in which antiviral medications are taken to interrupt sexual transmission of the virus. It is now being recommended by the WHO for, it seems all sexually active gay men. Actually it’s not quite that stark – they continue to recommend condom use as well. Despite this, many will probably see this as a recommendation to rely on PrEP as an alternative to condoms.
The WHO recommendation is a population based proposal, a public health recommendation as opposed to recommendations for specific individuals. Recommendations for individuals are different because they take into account individual circumstances, such as the extent to which a specific person is at risk. Population based recommendations are recommendations made across the board, in the case of the WHO, addressed to all men who have sex with men.
While assuring us that the recommendations are evidence based and providing the customary explanation of how the strength of evidence is graded, we learn that the WHO has made a sweeping worldwide population based recommendation on evidence provided by just one randomized study! This was the iPrEx study, which was beset with interpretative difficulties, not least because few took the medication as directed, if at all.
We simply do not know enough about PrEP to make a sweeping population based recommendation. . We have little idea of what adherence to the medication might look like in various populations, we know little about the degree of protection in specific sexual acts. Different sex acts carry different risks, for example, to the receptive or insertive partner in anal sex. Also, how effective is PrEP in situations of exposure to high and low viral loads. In addition we have little idea of the extent to which condom use will be abandoned.
It’s clear that there is a widespread view that PrEP is an alternative to condoms, despite official recommendations stating that PrEP should be part of a comprehensive prevention approach that includes condom use.
A more balanced response would have been a call for more research, and importantly, for a fuller description of those individual situations where PrEP use is a rational preventative intervention at the present time.
The use of PrEP by an individual is very different. The degree of risk to individuals will vary considerably and on an individual basis PrEP use can be a completely appropriate intervention in situations of very high risk, even if we do not have precise information of its efficacy without condom use. The use of PrEP could also be considered when there is an inability to maintain an erection with a condom. It might be an option to enable a fuller sexual expression among what is probably a large number of men whose difficulty with condoms, for whatever reason, stands in the way of satisfactory sex. Medical supervision is also more likely in individual situations. It is important to check for HIV infection and to monitor for sexually transmitted infections and drug toxicities.
Monitoring for sexually transmitted infections is important. Since PrEP alone offers no protection from the transmission of infections that might be interrupted by condoms we might expect an increase in such infections with a wide roll out of PrEP. The current increase in sexually transmitted infections among gay men in some cities is most likely attributable to an increase in unprotected sex. Many sexually transmitted infections facilitate the transmission of HIV which may be another factor that could drive an increase in new HIV infections.
The way PrEP has been promoted during the past few years has surely contributed to the poor support received for prevention education. One way in which this has happened is the shifting of budgets for prevention to those entities, private or government insurers that pay for drugs used in biomedical prevention.
There seems to be a widespread view that prevention education does not work. But we know that it can work. The adoption of safe sex practices including condom use in the early 1980s curbed the spread of the epidemic, although admittedly conditions are not the same today. There is little support for continued condom use, and rather than take the view that condoms don’t work, we might try to understand the obstacles that stand in the way of effective prevention education.
If prevention education has been ineffective it’s be because there has been so little of it, and what little there is has not been properly targeted. The move of the epidemic into African American communities during the 1990s was occurring in plain view yet the federal government was churning out expensive vacuous untargeted prevention messages in the form of “America responds to AIDS,” a futile exercise that helped to discredit prevention education.
I get the sense that some younger gay men feel they have missed out in not experiencing the abandon of the 1970s and see PrEP as a way to make up for this. The real lesson of the 1970s is that sex with multiple different partners on such a vast scale, as occurred in NYC in the 1970s, permits any pathogen that can be transmitted sexually to disseminate widely. That’s what started to happen with amebas and other intestinal parasites and HIV, and is happening with syphilis, gonorrhoea, herpes, hepatitis and many other infections. There surely will be others beyond HIV.
Since we really have very little information about PrEP, and almost none about its use on a population level such a broad recommendation by the WHO is absolutely inappropriate, so maybe faced with increasing HIV infections among gay men, the WHO is simply giving up and proposing an unproved intervention out of desperation. When I say unproven, I mean it is unproven as a viable population based intervention. Looked at this way, it’s a put down – a response that may be no more than gestural to people who continue to harm themselves by refusing to use condoms in sex with partners of unknown sero status.
This unwise WHO recommendation may also have the effect of increasing new HIV infections if it results in an increase in unprotected sex where adherence is inadequate.
I hope there will be a critical look at the WHO panel and funders responsible for producing such unhelpful recommendations.
Transmission of HIV from infants to their mothers.
This title may surprise some. In a paper (abstract, below) from a group at CDC I learned yet another HIV/AIDS related acronym. It’s CBWT, Child-to-Breastfeeding-Woman Transmission.
There have been several reports over many years of HIV infected infants born to mothers who were HIV uninfected. These infections were noted as early as the late 1980s in the former Soviet Union, in Libya in 1998, in Kyrgyzstan, Kazakhstan, Romania as well as in Africa. In every instance except in Africa, there cases were investigated with varying degrees of thoroughness. The sources of infection were invariably associated with contaminated blood, either from transfusions, or from procedures in unsafe healthcare settings, where for example sterilization of instruments is inadequate, or injection equipment is reused.
The infections noted in infants that were investigated occurred as outbreaks and all were determined to be nosocomial. Although infected infants born to uninfected mothers have been noted in Africa, remarkably, it appears that none have been investigated.
It will probably remain for a future historian to understand why cases of HIV infection in infants, horizontally rather than vertically transmitted, have yet to be investigated in Africa.
In those non-African outbreaks that were investigated transmission occurred through unsafe medical care, so what do we know of the safety of health care facilities in Africa ?
Unfortunately unsafe health care remains a problem in many facilities in high prevalence areas in Africa.
Taking Kenya as an example, Simon Colley has written in one of my blogs
“Where does Kenya fit into this picture? As UNAIDS admit, there’s not much data. But there is a document called the Service Provision Assessment which looks at conditions in various kinds of health facility, such as hospitals, clinics and pharmacies.
A few samples from this document may suffice to illustrate Kenya’s women capacity to prevent HIV transmission through unsafe injections and other healthcare practices: Between 10 and 15% of facilities don’t have adequate supplies of needles, syringes or latex gloves; between 55 and 70% don’t have running water or soap; many don’t have facilities for disposing of contaminated equipment or supplies of disinfectant; less than half have guidelines for infection prevention and less than 10% have guidelines for sterilization.
Although this document dates from 2004, we don’t know if there has been any change
There’s little doubt that unsafe health care is still a problem in Kenya and other high HIV prevalence countries. What’s not clear is how big a problem it is. Because, despite admitting that they don’t have the sort of data on unsafe health care that would allow an estimate to be made, UNAIDS and the WHO have failed to investigate or to carry out the research required”
As the title of this post indicates, infants infected either vertically or through exposure to contaminated blood are able to transmit HIV to seronegative women who breast feed them.
Mother to child transmission is the leading cause of HIV infection in infants. Some of these infected infants will be orphans and so place seronegative women who breastfeed them at risk. Wet-nursing is the complete nursing of another woman’s infant and still occurs as does cross-nursing which is the nursing of another infant by a woman while still nursing her own child. Estimates of the prevalence of these practices vary by region and the overall prevalence is not known.
Worldwide the greatest risk for CBWT is carried by seronegative mothers whose infants become infected through exposure to contaminated blood. Rates of CBWT were as high as 40-60% among mothers breastfeeding infants who became infected after birth.
This report on CBWT highlights the importance of unsafe health care facilities in the transmission of HIV. Of course HIV is not the only pathogen that can be transmitted in such settings.
A question that is unlikely to be addressed – it’s so rarely even asked, is: Why are infections acquired by exposure to blood, particularly in health care settings barely acknowledged, and never investigated when they occur in sub-Saharan Africa, but are investigated should they occur in Kyrgystan, Libya, Romania and elsewhere?
Why so few resources have been devoted to the improvement of health care facilities in developing nations is also puzzling. Could it be that like the provision of clean water and sanitation, improving health care facilities is not something that can generate much profit?
The benefits of improving infection control in these facilities extend far beyond effects in HIV transmission.
Perhaps it will be left to HIV activists in sub-Saharan African countries to alert funders and policy makers to the dangerous condition of many healthcare facilities in the developing world. HIV activists in the past have succeeded in bringing attention to important issues.
A group of individuals have been trying to bring attention to this issue for many years and I do recommend looking at the website that has been created to directly alert people in Africa to dangers in health care facilities with no or poor infection control procedures.
Unsafe medical practices in equatorial Africa about eighty years ago probably helped to set the epidemic in motion. Unsterile injections and transfusions by well-meaning colonial doctors provided conditions that enabled the initial spread of HIV (as well as of Hepatitis C and HTLV), before sexual transmission became the predominant way the epidemic advanced. This is described by Jaques Pepin whose account of the origin of AIDS is by far the most plausible.
To a greater or lesser extent, unsafe health care procedures are still contributing to the spread of HIV in parts of Africa. At least this source of HIV infections could be easily stopped.
A Review of Evidence for Transmission of Human Immunodeficiency Virus from Children to Breastfeeding Women and Implications for Prevention.
Kirsten M Little, Peter Kilmarx, Allan Taylor, Charles Rose, Emilia Rivadeneira. And Steven Nesheim.
The Pediatric Infectious Disease Journal Publish ahead of print.
Background: Child-to-Breastfeeding-Woman Transmission (CBWT) of HIV occurs when an HIV-infected infant transmits the virus to an HIV-uninfected woman through breastfeeding. Transmission likely occurs as a result of breastfeeding contact during a period of epithelial disruption, such as maternal skin fissures and/or infant stomatitis. Despite extensive epidemiologic and phylogenetic evidence, however, CBWT of HIV continues to be overlooked.
Objective: This paper summarizes the available evidence for CBWT from nosocomial outbreaks, during which nosocomially HIV-infected infants transmitted the virus to their mothers through breastfeeding. This paper also explores the CBWT risk associated with HIV-infected orphans and their female caretakers, and the lack of guidance regarding CBWT prevention in infant feeding recommendations.
Methods: We searched online databases including PubMed and ScienceDirect for English language articles published from January 1975 to January 2011 using the search terms “HIV”, “perinatal”, “child-to-mother”, and “breastfeeding”. The citations from all selected articles were reviewed for additional studies.
Results: We identified five studies documenting cases of CBWT. Two studies contained data on the number of HIV-infected women, as well as the proportion breastfeeding. Rates of CBWT ranged from 40 – 60% among women reporting breastfeeding after their infants were infected.
Conclusions: Poor infection control practices, especially in areas of high HIV prevalence, have resulted in pediatric HIV infections and put breastfeeding women at risk for CBWT. Current infant feeding guidelines and HIV prevention messages do not address CBWT, and fail to provide strategies to help women reduce their risk of acquiring HIV during breastfeeding.
Pre-exposure prophylaxis (PrEP) to prevent HIV infection with Truvada is not sufficiently effective
There is a similar
post on the POZ magazine website.
PrEP is a prophylactic intervention where uninfected people take anti HIV medications before sexual intercourse to prevent becoming infected with HIV. The use of a vaginal gel containing an anti HIV drug has also been tested.
The results of several trials of PrEP have been reported in the past year, all but one hailed as huge successes, with reported efficacies of up to 90% among those adhering to the treatment regimen.
The efficacy of PrEP in preventing HIV infection was so great that this intervention has been trumpeted as signalling a revolution in HIV prevention. A new era has opened up we are told; PrEP is a “game changer”.
With such enthusiastic coverage it may come as a surprise that none of the reports explicitly told us what the actual efficacies of the interventions were in preventing HIV infection, perhaps because they were so low as I’ll describe.
Maybe what’s even more startling is that this omission seems to have gone completely unnoticed, at least in the universally jubilant press reports and equally enthusiastic press releases from AIDS advocacy organizations.
How has this been possible?
The reason is that the results have been reported as reductions in relative risk only. This tells you nothing about actual risk reduction. What is reported is a percentage reduction in risk from a number that was never clearly stated. For example in the iPrEx trial of PrEP among men who have sex with men, the drug, Truvada, was reported to reduce the risk of infection by 44%. But 44% of what? We were not explicitly told, although it’s possible to calculate what it is.
In fact we can calculate that the absolute risk reduction conferred by Truvada is a measly 2.3%, a number nowhere to found in the trial report.
The relative risk reduction may have been 44%, but this translates into only an actual 2.3% reduction in absolute risk, as is shown below.
Reporting relative risk reduction only is the oldest trick in the book to exaggerate the effects of an intervention, used by salesmen, but apparently also by clinical researchers.
What makes the unquestioning acceptance of these reports of relative risk reductions achieved by PrEP even more remarkable is that there is a tremendous amount of material explaining the difference between relative and absolute risk reduction. Just type the words “relative risk absolute risk” into the Google search box.
Relative risk reduction tells you the percentage reduction in risk in the treated group compared to that in the group receiving placebo, or how much lower the risk with the intervention is relative to the risk to begin with.
If you are not clearly told what the risk is to begin with, then you can’t tell what the actual reduction in risk is when taking the intervention; all you know is how much lower it is than a number that’s not clearly presented to you.
Although not included in the iPrEx trial report there is information that allows one to calculate the absolute risk reduction conferred by Truvada. To do this we need to know what the risk of infection is to begin with.
This is the number of infections occurring in the placebo group over the time period of the study.
64 out of 1248 people in the placebo group were infected, which is 5.1%, or 0.051 in 1. (since then there have been additional infections reported at the Rome AIDS conference, reflecting an increase in the number of infections over a longer time period).
In the group receiving Truvada 2.8% of 1251 people were infected.
The absolute risk reduction conferred by Truvada is simply 5.1 minus 2.8 which is 2.3.
A 2.3% reduction in absolute risk conferred by Truvada is the more accurate measure of its efficacy. Hardly something to celebrate.
A 44% reduction in relative risk sounds much better, although far from spectacular,but unfortunately this number tells you nothing about actual risk reduction.
Relative risk reduction is calculated as follows:
It is the number of events in the treatment group subtracted from the number of events in the placebo group divided by the number of events in the placebo group.
On its own, relative risk reduction is not a helpful number.
Of much greater help to a person considering Truvada PrEP is knowledge of the actual risk while taking Truvada (over the period of the study, a median of 1.2 years).
That number is 2.8%.
Knowing the absolute risk reduction allows one to calculate another important measure. This is the number of people who need to be treated to avoid one infection (NNT).
From information contained in the trial report 45 people need to be treated to prevent one infection. I did not notice this number in the trial report nor was the absolute risk reduction
of 2.3% reported. NNT is a useful number as it allows one to estimate what it would cost to prevent a single infection with Truvada.
The cost of the drug is the least of it. A person taking Truvada PrEP needs to be monitored at regular intervals for toxicity and importantly, for infection, in order to avoid the inevitable emergence of resistant viruses as a result of sub optimal treatment.
If Prep is implemented on a large scale which some AIDS advocates seem to be calling for, but is unlikely to happen, then there may well be increases in new infections with viruses resistant to the drugs in Truvada in men who have sex with men, in IV drug users and in African populations.
PrEP is not a success, at least not with Truvada.
However such a failure was transformed into a triumph, part of the explanation is the use of relative risk reduction numbers with care taken to remain silent on absolute risk reduction.
Despite all the literature available to help people tell the difference between absolute and relative risk reduction, this evidently was a resource not used by those cheering along this ineffective intervention.
A very similar article has been posted at the aidsperspective site.
Pre-exposure prophylaxis, or PrEP, is an HIV prevention intervention in which anti-HIV drugs are taken to prevent infection. A safe, effective and affordable drug that could achieve this would be a powerful prevention intervention even possibly capable of halting the spread of the epidemic.
Last week we were told the results of the iPrEx trial that tested the efficacy of PrEP with Truvada, a combination of two anti-HIV drugs, in reducing new HIV infections among a group of men who have sex with men considered to be at high risk for HIV infection.
The announcement of the results was greeted with almost universal jubilation.
“That’s huge,” said a prominent AIDS researcher, “That says it all for me.”
“Today marks a major step forward in our quest to combat HIV among MSM
“This discovery alters the HIV prevention landscape forever,”
“….. the new data “represents the most promising development in HIV/AIDS since the introduction of triple combination drug therapy in 1996.”
“This is a game-changing trial result,”
Science magazine reported that..
“The researchers applauded and some even cried when they heard the bottom line”; “I have not cried this hard in years” – said one researcher.
These exultant cheers are usually reserved for the most momentous of breakthroughs.
Demonstrating that a drug could be safe and effective in preventing infection would indeed be a momentous breakthrough as already noted.
But the iPrEx results, far from representing such a breakthrough, indicated that PrEP, at least with Truvada, together with counselling and provision of condoms, reduced new HIV infections among men who have sex with men only modestly. It’s unlikely that the 44% reduction in new infections that was seen is of sufficient magnitude to make PrEP with Truvada viable as a public health prevention intervention. Moreover, as will be described there are significant safety concerns, a demonstrated danger of the emergence of drug resistant HIV, and the drug is far from affordable.
A 44% reduction in new infections is not huge; even those extolling the trial results would agree (at least I think they would, but who knows considering the over-the-top responses).
But what is most troubling is that the researchers have squeezed an efficacy of Truvada of over 90% by a questionable statistical sleight of hand, an improper use of sub-group analysis, a technique of data dredging that has been soundly discredited. I’ll return to this.
This has resulted in headlines such as “PrEP works – if you take your pills”, I don’t know if this will persuade some people to abandon condoms and religiously take their pills. Unfortunately, as will be explained, the type of subgroup analysis that apparently allowed investigators and commentators to confidently claim a greater efficacy of PrEP is not reliable. Maybe consistent use of Truvada will reduce new infections by over 90%. Maybe not.
For the moment staying with the ability to reduce new infections by 44%: As a public health intervention to be used on a wide scale, this degree if efficacy is just not good enough to justify using Truvada to prevent a life threatening infection. Even if the risk of infection is low this must be balanced against the gravity of the infection. About 3% of participants in the Truvada arm of the trial became infected as opposed to about 5% among those receiving placebo.
Perhaps it’s on this issue that I’m at odds with the huge acclaim given to the trial results. Maybe the prevailing view is that a 44% reduction in new infections is indeed good enough; some commentators are even discussing implementation.
PreP proponents like to compare it to malaria prophylaxis. If the efficacy of malaria prophylaxis were of the same order as that of Truvada in relation to HIV, I suspect many people might think twice before visiting an area where there was a risk of malaria.
Let’s take a closer look at the trial results, particularly the claimed greater degree of efficacy in compliant participants reported in the New England Journal of medicine.
I have commented briefly on this in my blog on the POZ magazine website.
The medication used in the trial, Truvada, is a combination of two anti-HIV drugs, FTC and tenofovir. It was compared with placebo in over 2000 men who have sex with men, considered to be at high risk for HIV infection.
The 44% reduction in new infections was achieved in conjunction with counselling, provision of condoms and monthly tests to monitor for infection.
This is not a good enough performance to justify widespread use of Truvada to protect against infection. The investigators then looked at blood and tissue levels of the drugs in people who became infected and those who did not. They found that those who remained uninfected had detectable drug levels while those who became infected did not.
They incautiously trumpeted this result as proving that Truvada works well if the pills are taken consistently – stating that in those who took their pills more consistently the relative risk reduction was well over 90%.
On the surface this sounds good. Almost all the commentators thought so.
However looking at the results in a sub-group of participants can be misleading. Most particularly in a sub-group that is defined after randomization; who would or would not comply with treatment could not have been known. The problems with subgroup analyses will be clearer after a short account of intention to treat analysis.
Intention to treat analysis is the most reliable way to analyse clinical trial data. In such an analysis participants are analysed in the group to which they were randomized, irrespective of whether they dropped out, or didn’t adhere to the treatment or strayed from the protocol in other ways. This seems counter-intuitive, but there are sound reasons why intention to treat is regarded as the best way to analyse trial data, among them that it more reliably reflects what happens in real life, rather than in a clinical trial. For example, one reason why pills may not work is because they are not taken. If they are not taken in a trial we have to be concerned that they may not be taken in real life. Take a look at this excellent explanation of intention to treat: Making sense of intention to treat.
As noted, the trial investigators made a lot of the sub-group analysis showing greater efficacy in those who took Truvada pills as measured by finding the drugs in blood and tissue samples.
This is surprising as the pitfalls inherent in such post-hoc sub-group analyses have been recognized for years. Commentators, some of whom are clinical researchers, in their over-the-top exultation at the results of the analysis in those compliant with Truvada may have forgotten about the treachery inherent in sub group analysis. A few commentators give the problem only passing acknowledgement.
This is a classic paper on sub group analysis:
Yusuf S, Wittes J, Probstfield J, Tyroler HA: Analysis and interpretation of treatment effects in subgroups of patients in randomized clinical trials.
Journal of the American Medical Association 1991 , 266:93-98
This is from that paper:
“Analysis of improper subgroups, though seductive, can be extremely misleading, because a particular treatment effect may influence classification to the subgroup. Thus, an apparent subgroup effect may not be a true effect of treatment but rather the result of inherent characteristics of patients that led to a particular response or to the development of side effects”.
In iPrEx the subgroups were categorized by events that happened after randomization, so the adherent group is an “improper” subgroup. “Subgroups of clinical trial subjects identified by baseline characteristics … is a proper subgroup while a subgroup determined by post randomization events or measures is an improper subgroup”.
In actuality the attention given to the subgroup that had blood and tissue drug levels is an example of the treachery of such sub-group analyses.
As an illustration, the reduction in new infections seen in this group may well have resulted from the following possibility.
People who take their pills consistently are more likely to use condoms consistently and in general are more attentive to risk. So if it were possible to do a subgroup analysis of people who adhered to placebo we might conclude that the placebo also works – (and it’s cheaper).
This is not so fanciful.
“In one study , those who adhered to the trial drug (clofibrate) had reduced
mortality; but those who adhered to the placebo pill had the same reduction in mortality”.
This is from:
Coronary Drug Project Research Group. Influence of adherence to treatment
and response of cholesterol on mortality in the coronary drug
project. Engl J Med 1980;303:1038-1041
A classic example of the pitfalls of subgroup analysis is what it demonstrated in ISIS-2, a trial examining the effects of aspirin after myocardial infarction. A subgroup analysis showed it was of benefit to all except people who were either Libras or Geminis.
Maybe Truvada taken consistently can reduce new infections by over 90%; maybe not. There was no basis for the investigators and commentators to present the first possibility with such overwhelming confidence.
We must accept that a 44% reduction in new infections is at this time the most reliable estimate of Truvada’s efficacy as PrEP. Although, the confidence interval , a measure of reliability, was wide.
We have an intervention that can reduce new infections by 44%, if taken in conjunction with a program of counselling, condom use, and monthly tests for HIV infection. That is the benefit. What about the down side?
The two most important are the development of resistance of HIV to the component drugs of Truvada and the toxicity of the drugs.
The utility in treating HIV infection of FTC and tenofovir – Truvada’s component drugs is lost if the virus becomes resistant to the drugs. Moreover, some mutations conferring resistance to these drugs can also affect sensitivity to some other drugs. The danger of resistance, and even cross resistance to other drugs developing when Truvada is used as PrEP is not a trivial concern. Truvada used as PrEP provides a suboptimal dose in treating established HIV infections. This is precisely the situation in which resistance is likely to develop. There were in fact two instances of developed resistance in the iPrEx trial in individuals who became infected, but undetected before the trial began.
Resistant viruses in the community are a danger to all, so the risk of generating resistance is not confined to the individual taking Truvada as PrEP.
What about safety?
The claim in many reports that Truvada is without significant toxicity is also misleading.
Maybe poor adherence has some bearing on the lack of significant toxicity.
A median of 1.2 years exposure to Truvada can tell us little about cumulative and long term effects. Experience with long term use of Truvada in HIV infected people makes concern about toxicity realistic. Renal toxicity, sometimes severe occurs not uncommonly. It’s mostly but not always reversible on stopping the drug. Thinning of bones, osteopenia and osteoporosis is also seen. There are additional adverse effects associated with the drugs.
There were small abnormalities in some parameters measuring kidney function among those treated with Truvada. Although these changes were reversible on stopping the drug, the fact that they were seen at all is a reason for great concern about the effects of longer term treatment.
With the experience we have gained from longer term treatment with Truvada, it is disingenuous to stress its overall safety from just 1.2 years of very inconsistent use.
It’s important to point out that for HIV infected individuals, the benefits of treatment with Truvada far outweigh the risks. For uninfected individuals, an entirely different risk benefit analysis must be made.
Despite the disappointing results of iPrEx, PrEP is important.
Why is PrEP important?
There are at least two important reasons.
PrEP could protect receptive partners in sexual intercourse, both men and women, who are unable to ensure that a condom is used by their partner and for a variety of reasons are unable to refuse sex . The best and most respectful way of addressing this would be to find ways to empower these individuals; in some way providing them with the means to protect themselves could be seen to also have the effect of perpetuating their subjugation and abuse.
But there are women and men who need protection now and providing them with a means to prevent infection that they can control is vital. This can go hand in hand with working to empower them and helping them to try to ameliorate or leave abusive relationships.
Sex is one of life’s joys. It is vitally important to the human experience.
Condoms can be a barrier to intimacy which for many is the most essential aspect of sexual intercourse, for both receptive and insertive partners. So recommending the use of condoms without acknowledging the significant obstacle they may present to a fulfilling sexual experience is a real problem. Pleasure is part of that fulfilment and for some insertive partners condoms are a significant impediment to experiencing it. A fully effective and safe means of pre-exposure prophylaxis may also allow the removal of a barrier to conception.
But people are different; for example some individuals have found that condoms can increase intimacy in the reassurance they provide concerning their and their partners safety.
We should never minimize or trivialize the difficulties condoms can present. We should also keep in mind that their use is the most effective means of preventing sexual transmission of HIV.
Their use will remain necessary in order to remain uninfected until we are free from HIV or a safe an effective PrEP method can be found.
These considerations, a prevention method that the receptive partner can control, allow conception and remove an impediment to full sexual expression are some reasons to work towards finding a safe and effective form of PrEP.
Truvada unfortunately has not proved to be sufficiently effective and safe.
A few words about prevention education and condoms:
The consistent use of condoms is the most effective means to prevent sexual transmission of HIV.
PrEP proponents agree but many go on to say that people just don’t use condoms consistently. This is an attitude that has apparently concluded that prevention education does not work, and more importantly, cannot work.
But how can one conclude that it cannot work when there has been so little of it? This has some analogy with the claims made for the efficacy of Truvada. It works, if you take the pills
If prevention education has been a failure, it’s not because it doesn’t work, but because we have not provided it well enough. There has been too little and most has not been properly targeted.
Proper targeting to those most at risk is critical. I have written about this. We need more and better prevention education.
The CDC now tells us that the group at greatest risk by far in the US is men who have sex with men. Nothing has changed except the ethnic distribution, so why are they only telling this to us now? For over twenty years we were told that AIDS was an equal opportunity infection making prevention education targeted to those at greatest risk even more difficult.
It’s only now, 25 years too late, that the CDC appears to recognize the urgency of providing prevention education to gay men.
Neglect of properly targeted prevention education, with encouragement for condom use and continuing support to sustain their use helped to allow the spread of HIV into African American communities in plain view while millions were spent on “America Responds to AIDS” a vacuous prevention message.
Similarly we have known for years that in the US younger men who have sex with men are at particular risk. We know where to target prevention messages, but we don’t it well enough.
We know that highly targeted prevention education, when crafted by the communities at greatest risk can work. This was demonstrated in the earliest years of the epidemic in San Francisco and New York City.
In 1982 when Michael Callen, Richard Berkowitz and I first recommended condom use to gay men in New York City, we stressed that in doing so it was important to celebrate sex, recognizing that for some individuals condom use, or perhaps more precisely, HIV, could present a barrier to its full expression. We have come far in freeing ourselves from long standing societal constraints that for too many have stood in the way of a fulfilling sexual experience burdening it instead with guilt. It’s important to take care in providing continuing support for condom use and recognize that for many they do get in the way. But it’s really HIV that’s getting in the way, and consistent condom use can help to bring it to an end.
Finding conditions where sex without condoms is safe is important. On the showing of iPrEx – despite its ecstatic reception, PrEP unfortunately is not yet ready.
At the moment consistent condom use is the best protection there is.
The often uncritical response to iPrEx should not persuade anyone that Truvada is a safe and effective alternative.
iPrEx is a large and complicated study. The investigators deserve the highest praise for completing this phase and having provided a result. It may not be the result so many hoped for. But providing clear information is a major advance.
This blog more or less duplicates that at the aidsperspective.net site, explained in the “about” page above.
HIV Disease and Positive Feedback. An additional comment.
AUGUST 31ST 2010
A previous post focussed on the positive feedback interaction between HIV replication and immune activation. HIV replication and immune activation reciprocally enhance each other.
While HIV infection is an essential cause of the immune activation that’s characteristic of HIV disease, there are other factors that also contribute to it. In that post as well as in the blog I write on the POZ magazine website, I described some of these additional factors that can add to immune activation. As noted, viruses of the herpesvirus family, cytomegalovirus (CMV) in particular are the most important of these worldwide, while in parts of Africa certain endemic infections may be of great significance in contributing to immune activation.
Since sustained immune activation, involving both innate and adaptive immunity is at the heart of the pathogenesis of HIV disease an understanding of how it is perpetuated is critical.
Evidence for activation of innate immunity was noted in 1981, the year that AIDS was first reported, in the detection of large amounts of alpha interferon in the circulation of patients. We even knew then that interferon alpha and gamma could induce an enzyme, indole 2,3-dioxygenase (IDO), (IDO was known to be responsible for the inhibition of toxoplasma gondii by depletion of tryptophan in cells treated with gamma interferon) but we did not know then that this enzyme could contribute to the loss of T lymphocytes. Another observation of historical interest is that even before AIDS was first reported in 1981, interferon was known to preferentially inhibit CD4 lymphocyte proliferation in mixed lymphocyte culture.
Since immune activation and its effects, including inflammation, are harmful if sustained, there are mechanisms that can dampen it.
But in HIV disease, immune activation persists with continued deleterious consequences.
The reason I’m revisiting this now is that there is a question that continues to be bothersome.
HIV disease is not the only infection associated with long standing immune activation.
Several endemic infections in Africa are also associated with sustained immune activation, certainly not all – some even have a dampening effect on immune responses. TB is another example of an infection associated with chronic immune activation. In none of these conditions is there such a profound loss of CD4 lymphocytes as in HIV disease. While individuals with active pulmonary TB have been reported to have lower CD4 counts than healthy individuals, the numbers were well above 500.
Is the difference between sustained immune activation associated with HIV and that associated with other chronic infections in HIV negative individuals a matter of degree – is it a quantitative difference?
Could the mechanisms that dampen and check immune activation be impaired in HIV disease? These mechanisms include the secretion of cytokines that have anti-inflammatory properties, such as IL-10, IL-13, and TGF-beta, among others. Specialized immune system cells can also dampen immune activation. Tregs, a subset of T lymphocytes, have such a dampening effect. Although there are conflicting reports on the relationship of Tregs to HIV disease, it is known that HIV targets some of these particular T lymphocytes.
This graphic comes from my earlier post on positive feedback characteristics of HIV disease.
In this diagram HIV pathogenesis is represented by a circular process moving in a clockwise direction. It is started by HIV infection and can be propelled by a positive feedback association between HIV replication with immune activation. Immune activation is reinforced by CMV, and in certain settings, by some endemic infections. This is represented by the + sign in the diagram. Immune activation is retarded by those influences that dampen the immune response, including anti-inflammatory cytokines and Tregs, represented by the – sign in the diagram.
Here is a revised version of this diagram:
HIV disease progression is represented as moving clockwise in a circle, reinforced by sources of immune activation other than HIV and retarded by Tregs and other mechanisms that dampen immune responses. Tregs act as brakes, but HIV can directly make the brakes less effective.
Could critical differences between HIV disease and other infectious causes of long standing immune activation where CD4 numbers are relatively preserved, be the preferential targeting of Tregs by HIV and a different pattern of cytokine secretion?
I wonder if this revised representation of HIV disease lends itself to a more formal modelling process.
In this particular model a disease process is represented by a circular motion in a clockwise direction, with forces that both propel and retard it. Some predictions can be made.
The degree of immune activation at the time of HIV seroconversion would favour more rapid HIV disease progression. The set point – the level from which CD4 lymphocytes decline following an acute HIV infection, would be lower, and the subsequent rate of CD4 decline higher when HIV infection occurs in a person where there already is a higher degree of immune activation, compared to an individual where this is not the case. There already is some evidence in support of this possibility.
It’s well established that HIV disease progresses more rapidly with increasing age. Could an explanation for this be that immune activation increases with age – indeed, it’s been suggested that immune activation contributes to the aging process.
HIV disease progresses more rapidly in individuals with active TB. CMV viremia was noted to carry an adverse prognostic significance in HIV disease very early in the epidemic. There are but two examples, but there are many more of of a more rapid course of HIV disease in the setting of other infections caused by bacteria, protozoa, viruses and helminthes. Some are referred to in a previous post.
Are Treg numbers at seroconversion and for a period immediately afterwards related to subsequent disease progression?
Could treatment with anti CMV agents during acute HIV infection retard subsequent disease progression?
There already is some evidence that treatment of HIV during acute infection might slow the subsequent course of HIV disease.
The utility of any model of a disease process lies in its ability to provide a common explanation for disparate observations as well as to make predictions that can be tested by an analysis of available data or by experimentation.
Viewing HIV disease as a process with a positive feedback interaction between HIV replication and immune activation with forces that both enhance and retard this interconnection, provides a useful descriptive framework as well as testable predictions.