Saletan on Black and Gay Blood Donors

I see William Saletan, writing at Slate, asks the same question I was asking a couple of weeks ago, though of course he asks it better than I did. We're talking about the policy of not accepting blood donations from men who have had sex with another man even once since 1977. The abbreviation for "men who have sex with men" is MSM, it's more precise than "gay" or "homosexual."

The FDA bases its MSM policy on simple math. "Men who have had sex with men since 1977 have an HIV prevalence … 60 times higher than the general population," the agency observes. "Even taking into account that 75% of HIV infected men who have sex with men already know they are HIV positive and would be unlikely to donate blood," that leaves a population of MSM blood-donor applicants whose HIV prevalence is "over 15 fold higher than the general population."

So a 15-fold difference is good enough to warrant group exclusion. How about a nine-fold difference? According to the Centers for Disease Control, HIV prevalence is eight to nine times higher among blacks than among whites, and HIV incidence (the rate of new infections in a given year) is seven times higher. For black women, HIV prevalence is 18 times higher than for white women.

And these numbers understate the likely difference in risk to the blood supply. A recent CDC analysis of MSM in five cities found that while only 18 percent of the HIV-infected white men were unaware of their infections, 67 percent of the infected black men were unaware. If the awareness gap between blacks and whites overall is even half as great as it was among the men in this study—i.e., if blacks are twice as likely as whites to be unaware that they're infected, and therefore more likely to try to donate infected blood—then theoretically, black donors are just as risky as MSM donors. If it's OK to reject blood from gay men, what about blacks?

His links are very informative.

This is a multiobjective optimization problem, if I may say so. You are trying to maximize the availability of blood while at the same time minimizing the risk of accidental infection through transfusion.

Maybe it's easier to think of a comparable multiobjective optimization problem that does not have the connotational baggage. Think of speed limits on the roads. There are two criteria: you want people to be able to get to their destinations as quickly as possible, at the same time minimizing the numbers of fatalities and serious injuries from accidents. The ban on MSM blood donors is like setting the speed limit to ten miles per hour everywhere. The Beltway, interstate highways, school zones, everywhere, no one can ever go faster than ten miles per hour.

The effect of such a speed limit would be to optimize one of the two criteria. I'll bet almost nobody would ever get killed or seriously injured in car wrecks at ten or less miles per hour. You can see though that this solution fails to optimize the other criterion. Nobody would ever be able to get where they were going. Forget traveling, working in the next county, forget going out of your neighborhood, you can't do it at ten miles per hour. Speed limits have to optimize both criteria, travel efficacy and safety, over a general population.

In the same way, the point of collecting blood is to make blood available for people who need it. A 2005 survey by the Centers for Disease Control and Prevention found that 6.5 per cent of men age 25-44 had ever had oral or anal sex with another man. You would be taking approximately that percent of American males out of the donor pool by implementing a no-MSM rule. The policy has a cost: it results in fewer donors, making much-needed blood more scarce.

Saletan's point is on-target. If the reason for the rule was simply to decrease the risk of infection by banning a group of people with a high infection rate, then in a reasonable world you would not allow black people to donote blood, either. Of course, even if you supported a no-blacks policy with statistics, everybody would recognize the policy as racism. The question for blood donation is obviously not the color of somebody's skin, but whether they are infected with a deadly disease. And even though blacks are more likely to be infected with HIV, and even though they are less likely to know when they are infected, and thus are more likely to innocently show up to donate blood, the powers that be feel that the risk is acceptable. And most people agree that the risk is acceptable, all blood is tested, the chances of getting HIV from blood are now one in every two and a half million transfusions and that's not bad.

So why does the government accept black people's blood and not gay people's? There is only one possible explanation: gay cooties.