Blood Donation, Ideology, and Science

The FDA has shortened the deferral for men who have sex with men (MSM) for giving blood.

The new rules decrease the time down to a year, meaning that gay, bi, and closeted men must be celibate for a year in order to give blood. Understandably, this rubs a lot of liberals the wrong way. It is worth noting that there are two “flavors” of objection here. There are those who wish to lift the ban entirely; this article will more directly address them. Then there are those who would change the ban; this piece dips into that debate but it is much more complicated and I do not have a final recommendation there.

Liberals who are usually proud that the progressive wing is more interested in rational policy have deployed a series of arguments that ignore or distort the statistical reality of the public health issue. To be sure, there are good political reasons to support a different set of policies, but public health is not one of them.

To understand the relative risks here, we have to do some arithmetic. As a baseline, men who have sex with men account for about 8% of the population, with gay men being only a fraction of that. At the same time, about 60% of new cases come from that group. 8% of the population generates 60% of new HIV cases every year. Even a crude estimate here suggests that MSM are 17 times more at risk than all the behaviors that constitute not being a man having sex with men. Mileage obviously varies; it is not, for example, 17 times more risky to share needles than to have same-sex relationships nor is all MSM behavior created equal.

A duplicitous argument that gets made—though, I tend to think it gets made in good faith—is that the risks come primarily from behavior. This is true, to a point. The risk from anal sex, for example, is the same for heterosexual and homosexual intercourse provided one of the partners is HIV positive. This is duplicitous because assuming that the playing field is level distorts the practical risk. HIV prevalence is plainly much higher among men who have sex with men, and so the behavior is more risky.

The risks we are talking about, however, are small. The “eclipse period”, the time between becoming infectious and being able to test positive is about 2 weeks. With 30,000 new MSM cases every year, that means that each new case is undetectable for about 4% of that year. About 1,200 cases of new HIV cases from MSM are undetectable at a given moment. Donor rates are tricky, but if men who have sex with men give at about the national rate, 5% a year, that means that we’re looking at 2.5 people slipping past. Because donations are often split between plasma and red blood cells, that is 5 new cases. That is all at once not much and an unacceptable public health risk.

The second safeguard in place is a test with a 45 day eclipse period. Used by itself, lifting the ban would be a catastrophe, but the point is that it is used to catch those the first test might have failed on. This means that a 45-day deferral makes more sense. A 6-month deferral basically guarantees that this second test will not fail, and so the two tests taken together should make the blood-supply completely safe as safe as the deferral is respected. Those suggesting that a year ban is long have a point, but for the second test to be meaningful, the ban must be measured in months. The FDA will not move below a year because there is no study backing 6 months or less. I have the luxury as a blogger to spitball a bit.

It is worth reflecting here on one of the very few cases of transmission in the United States since 2003. A man lied to avoid a deferral, and infected a transfusion recipient with HIV. He may well have infected another, except the patient died and researchers were unable to follow up. This alone should temper the well-intentioned calls to lift the MSM ban in its entirety. If you are lying about your deferral, stop.

Now, the current ban is more than a little ham-fisted. While I obviously believe relative risk in MSM populations justifies a deferral that specifies MSM, limiting the deferral to anal-sex and other high-risk acts makes sense based on the risks of, for example, oral sex. Things are murkier on the issue of monogamous partnerships, but it is worth noting that heterosexuals are assumed to trust their partner. A heterosexual woman is asked if her partners have had MSM contact; it is hard to believe that those answering “no” are always right. Still, the numbers game being what it is, the FDA may not care. (Gay men are not inherently more likely to cheat, but they are inherently more likely to cheat with a man.) This gets us far enough into the weeds—and far enough from the lift-the-ban comments I had in mind—that I am going to stop shy of taking a firm stance about this specific change. I’d be interested what commentators think of the balance of both the hard risks and the very real respectability politics at work behind such a change.

There is another angle we could take as far as MSM specifications. We could say, as a matter of identity politics, that we do not accept singling out gay, bi, and closeted men and will instead use behaviors. By analogy, we do not use race as a category for deferrals despite the fact that a case could be constructed for it. In other words, factoring in politics may be legitimate, but it does not change the fact that lifting the MSM ban in a broad sense would be a catastrophe.

The lesson here, I think, is that liberals are low information voters just the same as conservative ones. We see discrimination against gay, bi, and closeted folks and assume it cannot be rational policy. The more sophisticated of us construct an argument around that and find advantageous evidence. The FDA has done themselves no favors by delaying a needed policy change and making homophobic comments during open discussions.

But it does not change the basic facts: there is a real risk to doing away with the MSM deferral.


One thought on “Blood Donation, Ideology, and Science

  1. If it’s behavior specific, then it should be *behavior* specific. Anal is significantly more likely to result in transmission – that should *mean* something in terms of the deferral. Unprotected sex is significantly more likely to result in transmission. In a committed relationship, using protection and disinclined to anal sex, idk, it’s super invasive questions but maybe that’s how the process goes. Sort of triage your risk – “okay, you answered ‘yes’ to ‘are you a man who has sex with men in the past year’, so we need to go to this section to assess how high-risk that sex was,'” basically.

    Idk, i can’t focus on this stuff because koREAAAAAA


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