Men having sex with men and blood donation: is there a game changer on the horizon?

U ntil a few years ago, most industrialized countries imposed a lifetime deferral from blood donation for men who ever had sex with another man. This quasi-universal policy was introduced in the 1980s because men who have sex with men (MSM) were recognized as a group at high risk for acquired immune deficiency syndrome, even before the human immunodeficiency virus (HIV) was identified. After the advent of HIV screening tests, this lifetime deferral policy was maintained, even if these tests would detect the vast majority of HIV-infected MSM donors. There were several reasons for justifying the status quo: early HIV screening tests may not have had optimal sensitivity; testing errors could happen; positive units could be mistakenly released for transfusion; untested units sometimes needed to be released on an emergency basis; and so on. The most worrisome concern was (and still is) the infamous window period, the early phase of infection when viral RNA or antibodies have not yet risen to a level that allows for a positive screening test of an infected donor. Another factor also strongly reinforced the status quo: the “dread factor” associated with the very real possibility of acquiring HIV through transfusion. Even though transmission of HIV by transfusion became extremely rare after the introduction of serologic testing, the tainted blood scandals of the 1980s and early 1990s was still very much in the public’s mind. Transfusion recipients, regulators, physicians, and the public in general had all the best reasons to demand that blood be as safe as can be. This was a fully justified expectation back then, and it is still the case today. But that does not necessarily mean that the status quo would indefinitely remain the only acceptable option. A case in point is what happened more recently in many countries: a more inclusive approach that imposes a temporary as opposed to a lifetime deferral for the MSM behavior. At the turn of the millennium, discussions started about the possibility of relaxing the lifetime deferral policy and imposing instead a temporary, time-based deferral on the MSM behavior, as was customary with other risk factors. The main argument went like this: A sufficiently long period of abstinence would ensure that all infected donors would be long past the window period, which is by far the main risk of accepting sexually active gay men for blood donation. The other risks (false-negative results, human errors, etc.) were considered to have become negligible: nucleic acid testing (NAT) was introduced in most jurisdictions, which not only further reduced the window period to a mere week or two, but also added redundancy to the HIV screening process. Also, blood operators now had robust quality systems in place that would greatly reduce the risk of clerical and operational errors. On these premises, mathematical modeling was used to quantify the impact of applying a temporary deferral policy on the risk to recipients. In most of these models, calculations showed an increase in risk, yet so small that it would not be noticeable in reality. In the United Kingdom, for example, it was estimated that a 12-month deferral policy would translate into one additional HIV-infected unit entering the blood supply every 3 years. What the models also predicted was a measurable and sometimes substantial increase in the number of donors who would be infected with HIV. This is because the models assumed that MSM who were temporarily abstinent still had a higher risk of being infected compared to nonMSM donors. However, these infected donors would all test positive, and their donations would be removed from the blood supply. Therefore, most models were fairly reassuring, such that support for the implementation of a temporary deferral policy slowly gained traction. In 2000, even before these modeling studies were conducted, Australia took the first step and went from a permanent to a 12-month deferral for MSM. It took a while before others followed suit, but eventually several countries also implemented a temporary deferral for MSM, including the United Kingdom, Canada, France, the United States, and others. This very large field experiment confirmed the main prediction derived from the models, that is, that there was no observable increase in the risk to recipients, starting with Australia, where the policy was first adopted. In fact, there is not a single documented case of HIV contamination that can be attributed to the implementation of a temporary deferral policy for MSM. Something else also became clear: The models had been overly pessimistic with respect to the impact of the temporary deferral policy on the overall prevalence of HIV in the donor population. As mentioned previously, these models predicted fairly substantial and measurable increases, from 73% to 3418%. The reality is that rates of HIV among donors were unchanged after the implementation of the temporary deferral policy for MSM. Either newly eligible donors were at no increased risk or they just never presented to donate. Other studies confirmed that abstinent MSM donors did in fact donate. They are most certainly at very low risk for HIV, much lower than what the models had assumed. Given doi:10.1111/trf.15706 © 2020 AABB TRANSFUSION 2020;60;437–440