OA1-AM24-ST-27 - Assessment of Blood Safety Implications of Increasing Use of HIV Treatment and Prevention Therapies

Following US FDA Guidance allowing adoption of individual donor assessment (IDA), most blood services have adopted it. The donor history questionnaire (DHQ) asks about use of therapies to treat HIV infection (antiretrovirals-ARVs) and prevent HIV infection (preexposure prophylaxis or postexposure prophylaxis-PrEP-PEP). The ability of blood screening assays to detect infection if people are taking ARVs or PrEP-PEP is a blood safety concern. We report rates of disclosure of ARV and PrEP-PEP use following the adoption of IDA at our blood center and through modeling assess the risk of transfusion-transmitted (TT) HIV assuming nondisclosure of PrEP-PEP use and HIV breakthrough (b/t) infection.

Study

Design/Methods:

DHQ response rates for use of ARVs, oral (oPrEP-PEP), and injected (iPrEP) are reported. To estimate the transmission risk of undetected HIV infection, we developed a risk day equivalents model of the probability of a PrEP-PEP b/t HIV infection being infectious and not detected using NAT or serology in a donation. Assumptions are from the literature on rates of undisclosed PrEP use in donors, viral dynamics following b/t infection and detection delays from PrEP clinical trials. We defined two scenarios with different assumptions using the most common risk day estimates from simulations.

Results/Findings:

For the IDA period 8/20/2023 to 3/31/2024, among 810,666 allogeneic donor DHQ responses 0.006% and 0.008% of female and male donors, respectively, reported ever taking or being unsure about taking ARVs to treat HIV. So far, we have observed robust antibody detection of donors who did not disclose taking ARVs to treat HIV at the time of donation in routine donation screening (AABB 2023 abstract OA4-AM23-ST-13). For PrEP-PEP, 0.006% and 0.035% of female and male donors (p< 0.05), respectively, reported taking or being unsure about taking oPrEP-PEP in the last 3 months, and 0.028% and 0.016% of female and male donors (p< 0.05), respectively, reported use or being unsure about iPrEP use in the last 2 years. The modeled risk of a TT HIV PrEP-PEP b/t infection is 1 in 12.3 million (m) and 1 in 2.3m plasma transfusions, under optimistic and pessimistic assumptions, respectively. Risks are lower for RBC transfusions (Table). Under unlikely parameter combinations, the 95% CI of simulated b/t risk days could be up to about 4 weeks which would increase risk.
 

Conclusions:

In the early IDA period donors are disclosing ARV and PrEP-PEP use, which is reassuring. All responses were more common in first-time donors, oPrEP-PEP more common in males, and unexpectedly iPrEP more common in females. Monitoring disclosure of ARV or PrEP if donors return for future donation is needed. Our initial assessment of additional TT HIV risk to the blood supply is comparable to existing residual risk. Risk estimates will be refined as new data become available, including the most likely risk day distribution.