Who’s afraid of a gay man’s blood? We are.

Britain is the latest country to lift its lifetime ban on blood donations from men who have sex with men
Adam Piotrowski/Flickr

The Statement: “In our case, we’re absolutely certain that going from a lifetime deferral to a five-year deferral or even a one-year deferral … would absolutely make no difference in terms of the risk of HIV (transmission),” Marc Germain, Héma-Québec, 09/08/2011

Starting in November, the United Kingdom will join South Africa, Australia, New Zealand, Japan and other countries that have lifted the lifetime ban on blood donations from men who have sex with other men (MSM) and instead impose a 12-month deferral period after oral or anal sexual contact with a same-sex partner has occurred. This rule will apply whether or not a condom was used.

The policy change is based on the findings of the independent Advisory Committee on the Safety of Blood, Tissues, and Organs, which reviewed the evidence on donor selection criteria, taking into account improvements in blood testing, monitoring from countries with shortened deferral periods, and donors’ compliance with the ban. They concluded that the science “no longer support[s] the permanent exclusion of men who have had sex with men.”

Yet, deferral periods for MSM still vary widely from one jurisdiction to the next. 

In Sweden, Japan, and Australia, the wait is one year. In New Zealand, it’s five. In South Africa, six months from a man’s last same-sex encounter is enough. In Italy, the restriction lasts for four months after sex with a new partner. Canada—along with the US, France and many other countries—continue to refuse MSM donors all together. Why this variation?

To find out, Science-ish called Dr. Greta Bauer, an epidemiologist and biostatistician at the University of Western Ontario. (Bauer was an expert witness in the Freeman vs. Canadian Blood Services trial of a gay Ontario man who defied the donor ban.)

Dr. Bauer explained that in the early, panicked days of the AIDS epidemic, broad exclusions seemed necessary. “We needed these deferrals,” she said. “They made sense before we have highly sensitive testing for HIV.” In 1983, the Canadian Red Cross Society and later, the Canadian Blood Services, prohibited blood donations from men who have had sex with another man at any time since 1977—the year it is believed HIV infection transmission took off. In Canada, that’s still the rule today, meaning MSM donors need to have had a 34-year (and counting) period of celibacy in order to give blood.

Since then, however, much has changed.

The point of the deferral is to limit the number of infected units collected. (All collected blood is still tested.) The current window for HIV testing is about two weeks. For Hepatitis B, it’s about two months. A year is believed to be more than enough time to catch diseased blood, which is one reason why countries like the UK have switched from life-time bans to 12-month deferral periods.

Last year, Australia—a country with a population and HIV-epidemic profile similar to Canada—provided perhaps the best-available evidence to show that one-year deferrals work. The Australian Red Cross published in the journal Transfusion on the effects of reducing the MSM deferral to one year. The study looked at five-year periods before and after the policy change, and found no increase in the number of HIV-infected units collected, despite a 900,000-unit spike in individual blood donations. In both periods, 24 units of HIV-infected blood were discovered. “This is the first real empirical evidence we have based on a country changing its donor policy,” said Dr. Bauer.

This evidence contradicted theoretical models that most countries with a lifetime ban on blood from MSM use to justify their donor policy. Studies in the U.S., Canada, and the UK, estimate that there would be a small but non-zero risk associated with reducing the MSM deferral to one or five years. (In Canada, it is postulated that one additional HIV-infected unit could enter the blood supply every 16 years as a result of human error.) For Health Canada, this increased risk—though negligible—is still enough reason for the lifetime exclusion of a potential donor group.

But as we know, said Dr. Bauer, “The existing theoretical models show that if we shorten the deferral period from lifetime to one or five years, we would see a small increase in HIV-infected blood collected, and the real risk to the blood supply would be the erroneous releases of HIV-positive units from quarantine as a result of human error.” That quarantine release risk is based on the assumption that there would be more HIV-infected units collected but the empirical data from Australia show that there was no such increase. “This speaks to our inability to predict these things using theoretical models,” Dr. Bauer observed.

The policy in place at Canadian Blood Services is also based on the premise that gay men are more likely than others to contract HIV. While this may be true, critics point out that studies of HIV in gay men do not reflect the current policy, which covers any man who has had a sexual encounter with another man since 1977—not just sexually-active gay men.

There are also the problematic assumptions about the risks MSM donors pose compared to other risks involved in blood transfusion. Dr. Eleftherios Vamvakas, the chair in transfusion medicine at Cedars-Sinai in Los Angeles, has published extensively on this issue. In one review, he compares the relative risk of reducing the lifetime blood donation deferral for MSM to “currently tolerated transfusion risks,” and finds that the risks associated with a shorter deferral period are much smaller than the tolerated transfusion risks in general, “so small in absolute terms that the ethical question of fairness to the MSM group justifies the change in policy.”

Science-ish is a joint project of Maclean’s, The Medical Post, and the McMaster Health Forum. Julia Belluz is the associate editor at The Medical Post. Got a tip? Seen something that’s Science-ish? Message her at [email protected] or on Twitter @juliaoftoronto