On the MSM Blood Ban

CGFb3c7W0AAW9b7.jpg:largeOpposition to the UK’s (and others’…) ban on blood donations from (rather awkwardly termed) “men who have sex with men” comes to our collective attention now and then – for instance when Michael Fabricant put forward a parliamentary motion calling for its end last year.

This morning it popped back to my personal attention when a leaflet popped through the door. “If you could give up just 1 hour of your time to save or improve up to 3 lives, would you do it?” it asked. Well, yes – I would. I can’t though. Last week, it popped back to my attention when I saw the blood donation vans parked on campus – “Give Blood” they say. Well, yes – I would. I can’t though. The privilege of the majority is not being constantly aware that you’re in a minority and seeing that demonstrated through opportunities – however altruistic – denied to you. Especially when that denial is rooted in homophobia.

“NO” – you’re thinking – “it’s not homophobia, MSM have an objectively higher likelihood of being HIV positive, and we need to keep that out of the blood supply.” It’s all true. MSM are more likely to be HIV positive, there’s no denying that fact. Nor can you deny that there is slight risk that the window between infection and seroconversion means screening is not 100% effective in keeping an HIV positive person’s blood out of the blood supply. The real question, and my real objection to this ban, is why on earth we have chosen to stratify the population into MSM and non-MSM. I’ll explain, shortly, why I think this distinction is homophobic, but I think it’s worth restating the challenge faced by the Blood Service to give a common basis for understanding.

The goal of the blood service should be – and, despite what I think is misguided reliance on dubious science, is – to keep HIV positive blood out of the blood supply, so that all of us, should we ever need it, can feel confident in receiving a transfusion. In an ideal world, people who are HIV positive (or who carry other diseases like Hepatitis, or vCJD) would be excluded on safety grounds and everyone else would be encouraged to give blood. Keep that simple goal in mind.

The problem, then, is that we don’t have a completely reliable – or even “good enough” – test for HIV. It’s possible to be infected for months or even years prior to the virus becoming detectable through an antibody test (although the average is about 6 weeks) and only about half of people will develop symptoms during seroconversion. So now the challenge is a little more complex, how do we segregate the population into those considered low risk and those considered too high-a-risk to donate blood?

Those people who know they are HIV+ can be screened simply by asking them “Are you HIV+?” – This gets rid of the 80% or so (HIV Aware, 2012) of people who are diagnosed. Of the remaining 20%, many will be picked up by screening, having been infected long enough to develop HIV-specific antibodies that will be detected by the antibody test used by the UK Blood Service. The other HIV test, a nucleic acid test (NAT) is 95% effective in detecting HIV infection in individuals infected for 17 days or more. That leaves a small group of people, who have been recently infected, that cannot be removed from the donor pool either by asking them about their status or by screening their donations – the undiagnosed and undiagnosable-at-point-of-donation HIV+ population – UUHIV+.

In mathematical terms, we’re starting with a single population (of all of us, excluding known HIV+ people), with some known proportion of UUHIV+ people remaining. This is a prior probability distribution – It’s the distribution of risk that we know about, in the absence of any more information about the population.

The challenge that we have in practice, then, is to identify some set of criteria that we can use to improve our probability distribution – to learn more about the likelihood that a given person is UUHIV+.

Excluding every man who has had sex with another man in the last 12 months does do that. But so does excluding all black people, everyone below 60, or, (for a massive reduction in risk, at the expense of supply) everyone who isn’t a gold-star lesbian.

Quite reasonably (and probably in part because most of institutions are now clued-up enough about racism to spot it in their own policies) the UK Blood Service does not exclude all black people from donating blood. They do have restrictions on people who have visited certain countries in the last 6 months, though. The point is that we need to select screening criteria that are reliable and specific.

While it’s undeniable that more MSM people are HIV+, and therefore probable that, proportionally, more MSM people are UUHIV+ than the general population, it’s equally undeniable that a) the vast majority (96% for most of the UK, 92% for London *) MSM are not (and never will be) HIV+ and that b) large numbers of non-MSM people are HIV+.

It’s also undeniable that the MSM group covers a massive spectrum of risk: from monogamous long-term couples to [what’s a nice term for megasluts?], from the regularly-tested condom-obsessive to the GUM-avoiding bareback fanatic. The use of a criterion as blunt as “MSM” knowingly excludes those with negligible risk of being UUHIV+ – those who are demonstrably lower risk than many non-MSM people who ARE allowed to give blood.

Meanwhile, straight [nice-term-for-megasluts] are not excluded on the grounds of sexual behaviour – unless they think they might have had sex with an MSM.

Fundamentally: HIV is not created when two men have sex – HIV is transmitted from an HIV+ person to someone else, usually sexually. HIV transmission is not so much a function of the gender or sexuality of the people you’re having sex with, but the prevalence of HIV within the network of people you’re having sex with. A homogeneous network of two – the monogamous HIV-negative diad – isn’t at risk. In fact, the pre-1980s homogeneous network of millions wasn’t at risk until HIV was introduced into that network. It was the individual behaviours within that network – promiscuity and little use of condoms – that facilitated the rapid spread of HIV among members. Two MSM in a monogamous sexual relationship are at infinitely less risk than a non-MSM with many casual partners – the fact that MSMs, as a result of social factors (such as homophily, historic ghettoisation and culture), are at statistically higher risk is a rough correlation only.

Why, then, is being MSM in itself, rather than sexual participation in a broader “at-risk” network, used to screen blood donors? The UK ban was introduced during the early days of the AIDS epidemic – When we knew far less about HIV/AIDS but did know that it affected the gay community most. A ban at that point – in the absence of a clear understanding about what caused AIDS and no time to do the science necessary to establish specific screening criteria – was justifiable.

“Gay” is largely a term of self-identification and so, to your typically positivistic natural scientist, rather too wooly. Men who have sex with men, is, in terms of who it includes, far more objective. With very few edge cases (and only a little uncertainty about what constitutes “sex”) we all know whether we fit into that category.

Despite our knowledge that merely having sex with other men does not lead to HIV infection, and the fact that MSM covers such a wide range of behaviours with such varying degrees of HIV risk, it is still used as an objective and scientifically useful way to categorise people. What debates about objectivity (MSM) vs subjectivity (“gay”, “queer”, “on the D/L”) miss is the extent to which this division is arbitrary – and a distinction between two broad groups, MSM and everyone else, is increasingly arbitrary given documented social changes towards “post-gay” identities, social networks and hence behaviours. If MSMs ever were a homogenous group, they surely aren’t today.

Using MSM as a medical distinction blurs a whole range of complex factors, some of which correlate with HIV risk and some of which are co-incidental. MSM is a distinction that arises, in large part, because of how sexuality has come to define identity and social connections. Only a society in which a continuous spectrum (the Kinsey scale) was awkwardly divided into two discrete groups would even have stumbled into such a categorisation for epidemiological purposes.

Fundamentally, that is why the MSM blood ban is homophobic. It is a ban that denies our individual autonomy, our own understanding of (and appetite for) risk and instead reduces us to a sexuality because that’s how history has defined and marginalised us for centuries. It is a ban justified by a distinction based on two apparently objective groups, but which in reality is a distinction that results from the historic ghettoisation of MSMs, and which today is more and more arbitrary.

Yes, excluding MSMs from donating blood reduces the risk of UUHIV+ individuals donating blood, but it reduces the risk LESS than screening based on individual risk profiles and at the expense of a great deal of supply for a blood service which, it constantly tells us, is often under-supplied.

I want to see a comparison of the effectiveness of screening based on “Have you (a male) had sex with another male in the last 12 months?” and “Have you (a person) had sex with a new partner in the last six months?”, or “Have you (a person) had sex with more than three people in the last twelve months?”. These questions are justified by our increasingly detailed model of HIV transmission, and are not grounded in the arbitrary social divisions of our great grandparents. These questions send the message that your behaviour is what matters, and not your sexuality – If that’s not a helpful public health message then I don’t know what is.

If it turns out that asking “Are you an MSM?” is more effective at screening out UUHIV+ individuals from donating blood, then we should stick with it. Somehow, though, I doubt it would be.


* Although, even if you knew how MSM people had HIV (which is possible), since nobody can agree how many MSM there are (estimates of the “gay” population ranges from 2% to 10% of the UK population, with much of government going for something around 6%), stating what proportion are HIV+ is more akin to divination than actual statistics.

(HIV Aware, 2012) http://www.hivaware.org.uk/facts-myths/hiv-statistics