#OA2-AM25-MN-04 - Assessment of Donor Presentation Times Relative to HIV Acquisition During Different Deferral Policies in the U.S. Based on Quantitative Biomarker Testing

Background/Case Studies: The potential impact of ‘test seeking’ behavior among blood donors has long been a blood safety concern, because donating to primarily get tested for HIV in response to self-perceived risk of HIV acquisition could increase the likelihood of infectious window period donations. We sought to objectively evaluate, using laboratory marker-derived estimates of the duration of HIV infection, whether changes in HIV-infected donors’ presentation behavior occurred as donor eligibility policy evolved in the U.S.. The study was conducted by the Transfusion-Transmissible Infections Monitoring System (TTIMS), which has monitored infectious disease markers at four large blood collection organizations, as time-limited deferral policies for several risk behaviors and individual donor assessment (IDA) were implemented.

Study

Design/Methods: We estimated the duration of infection at the time of HIV-positive donation for confirmed NAT reactive donations, with or without antibody reactivity, using additional TTIMS laboratory testing. The duration of infection in NAT yield donations was based on quantitative viral load using Fiebig’s exponential viral outgrowth model and doubling time. In NAT and serology concordant donations, the duration of infection was estimated using the normalized optical density from the limiting antigen (LAg)-Avidity assay in a novel Bayesian approach, treating the interdonation interval of repeat donors and a single-sided window for first-time donors as an infection time prior, to obtain a posterior for duration of infection. The method was proposed by Sempa et al. For each donor, an infection acquisition time point estimate and credible interval was derived. Medians and interquartile ranges of infection time point estimates were obtained during each of four deferral policy periods as well as p-values using the Mann-Whitney test for difference from the indefinite deferral period.

Results/Findings: The median estimated duration of infection in confirmed HIV-reactive first-time donors during the indefinite deferral period was 398 days, and 618.5, 944 and 627 days during the 12-month, 3-month and IDA periods, respectively, with wide interquartile ranges (Table 1). The only statistically significant difference was the increased duration of infection in the 3-month compared to the indefinite deferral period (p=0.006). The median estimated durations during the four periods for repeat donors were 228, 188.5, 210 and 166 days, respectively, with no statistically significant differences (Table 1).

Conclusions: Average durations of infection did not yield any evidence of increased test-seeking behavior after implementation of time-limited deferrals or IDA, suggesting no increased HIV risk to the U.S. blood supply.