HIV Pre-Exposure Prophylaxis, Blood Donor Deferral, Occult Infection, and Risk of HIV Transmission by Transfusion: A Fine Balance Between Evidence-Based Donor Selection Criteria and Transfusion Safety

Pre- and postexposure prophylaxis for human immunodeficiency virus (HIV) are key to reducing the transmission of this virus. Furthermore, low-toxicity, long-acting formulations provide additional clinical benefits, in particular easier adherence to treatment and prevention. However, breakthrough HIV infections can occur despite the use of pre-exposure prophylaxis (PrEP), mainly due to suboptimal adherence or multi-drug resistant HIV strains. Albeit rare, PrEP breakthrough infections have also been reported in fully adherent patients. Should such breakthrough infection occur in an eligible blood donor, PrEP might suppress viremia and delay antibody seroconversion, thereby masking the infection and increasing the risk of transfusion transmission. This possibility has raised concerns in the blood transfusion community but remains little documented. Therefore, a literature search was performed to assess the state of knowledge on the risk of PrEP breakthrough infection, with a particular focus on the risk of HIV entering the blood supply. Evidently, PrEP breakthrough infections are rare, although the risk is not zero. Moreover, a fraction of individuals — including blood donors — do not disclose PrEP use according to various surveys and measurements of HIV PrEP analytes. Additionally, viremia and seroconversion may remain undetectable or close to the limit of detection for a long time after cessation of PrEP, particularly with long-acting antiretrovirals. Therefore, current recommendations to defer donors for at least 3 months after the last dose of oral PrEP or 2 years for long-acting PrEP appear justified, as they safeguard the blood supply and public trust toward the system. These recommendations help to safeguard blood safety and public trust in the blood supply.