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Technical solutions to social issues?

T here has always been a social dimension to infectious disease, but this was not really a focus in transfusion medicine until the emergence of HIV/AIDS. HIV infection and AIDS were feared due to an invariably fatal outcome for which various demographic and behavioral groups were deemed to be at elevated risk, leading inevitably to the construct of “risk groups.” To be in a risk group was devastating; not only was it a potential death sentence, but it also was socially sensitive and potentially demeaning. The intersection of risk and transfusion medicine involved the need to assure patient safety while facing issues of sexual and other risk behaviors among individuals presenting to give blood. Eventually, regulators in the United States and internationally established requirements that, in effect, resulted in the indefinite deferral of risk group members from donating blood. A primary risk group in the United States was (and still is) men who have had sex with men (MSM), who were until recently deferred if they acknowledged having had sex, even once, with another man since 1977. That was the year when it was thought that HIV had been introduced into the United States. Within the past 2 to 3 years, the equivalent of a permanent MSM deferral has been reduced to include only those who acknowledge MSM in the previous year. The policy has been widely characterized as discriminatory to MSM, recognizing that the behavior and lifestyle of MSM, just like that of heterosexuals, is heterogeneous. While the reduction in the time limit is rational, it has not eliminated the perception of discrimination among many MSM. We will return to this issue later. While demonstrating forward momentum, other limitations to a reduction in the MSM time-based deferral, at least in the United States, include that only a small number of prior MSM donors have presented to donate, and as mentioned, MSM still represents the highest risk group for HIV infection in the United States. In 2016, 67% of diagnosed HIV infections in the United States were attributable to MSM with the greatest increase in risk in the 13to 29-year-old age group, of which black/ African American MSM account for 49%. In South Africa, where the overall prevalence and incidence of HIV are much higher than in the United States, the social impact of HIV/AIDS on transfusion medicine is somewhat different in nature, but nevertheless instructive. As outlined by Vermeulen et al. in this issue of TRANSFUSION, the major risk group for HIV infection is the black majority population. It should be noted that only in the recent past (1994) was white minority rule eliminated in South Africa and replaced by an egalitarian, multiracial social structure. Nevertheless, the South African National Blood System (SANBS) continued to draw most of its donations from the minority white population and structured a risk management system for donor safety on racial grounds, effectively eschewing many donations from black African donors. This practice was considered within the judicial system and was declared discriminatory and unsustainable. The blood system cured the situation by a number of measures, but most notably by welcoming all donors, enhancing black African representation and implementing individualdonation nucleic acid testing (ID-NAT). South Africa was the first country globally to implement ID-NAT nationwide. The bottom line of these changes was remarkable, as noted by Vermeulen and coworkers. Within the 10 years from 2005 to 2015, the proportion of donations from black African donors increased from 6% to 30%, and among first-time black African donors from 19% to 54%. At the same time, the overall estimated residual risk of HIV transmission decreased from 24 per million donations to 13.4 per million, even though the black African donor population had an HIV infection rate 30 times greater than that of non-black donors. In other words, careful use of a specific testing strategy permitted acceptance of a muchhigher-risk subset of donors, while improving the overall safety of the system. ID-NAT interdicted 481 (1:16,100) seronegative donations considered to be in the infectious window period, 98% of which were subtype C (whereas subtype B is the clade commonly identified in the United States). Residual risks were estimated using incidence multiplied by the window period, with incidence calculated using the window-period/NAT-yield ratio model. ID-NAT appears to be the most sensitive test system currently available, at least in the context of the seronegative window period. Even so, Vermeulen et al. noted that, over a 10-year period, representing 7.7 million donations tested by ID-NAT, one HIV transmission from an RBC component did occur (0.13/million), and more may have occurred but were undetected (i.e., of the almost 3000 suspected HIV transfusion-transmissions investigated, a definite cause could not be determined for 63%). Even so, this was a 20-fold reduction as compared with the period prior to ID-NAT when two cases per year were observed. In an earlier study, Vermeulen et al. reported a single hepatitis B virus (HBV) transmission from an RBC unit during the HBV seronegative window period (0.34/million) versus an estimated residual risk in the seronegative window period of 25 per million donations. These breakthrough infections can be compared doi:10.1111/trf.15081 © 2019 AABB TRANSFUSION 2019;59;9–11