OA2-AM24-ST-27 - Deferrals for Pre-Exposure Prophylaxis (PrEP) for HIV Before and After the Switch to Sexual Risk Behaviour Screening

Individuals who become infected with HIV while on pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP) or shortly after discontinuing therapy may have altered viral kinetics and testing results. Since 2019, donors are asked about PrEP/PEP use in the last 4 months and deferred while on treatment and for 4 months after treatment cessation.  In 2022, time-based deferrals for men who have sex with men were replaced by sexual risk behaviour criteria; all donors are deferred if they had a new partner and anal sex or more than one partner and anal sex in the last 3 months.   We assessed donor deferrals for PrEP use in the 18 months before and after this change.

Study

Design/Methods:

Data on donors with a deferral code for PrEP/PEP was extracted from our National Epidemiology Donor Database (NEDD) and their donation file reviewed to assess if deferral was for PrEP or PEP, and if additional deferrals were applied on the same donation.  Deferral rates pre-implementation (March 11, 2021-Sept 10,2022, period 1) and post-implementation (Sept 11, 2022-March 10, 2024, period 2) were compared, and p values calculated using Fisher’s Exact Test.

Results/Findings: A deferral code for PrEP use was applied to 71 out of 1,187,100 donations in period 1 (5.98/100,000), and 124 out of 1,184,784 donations screened in period 2 (10.47/100,000, p=0.0001).  The percentage of coded donors deferred for PrEP use alone (no other deferral applied) was 61% in period 1 (43 out of 71 donors coded for PrEP use) and 63. in period 2 (78 out of 124 donors coded for PrEP use), the deferral rate for PrEP use alone 3.62/100,000 in period 1 to 6.58/100,000 in period 2 (p=0.0014). Other reasons for deferral in PrEP use donors included MSM in period 1, anal sex with a new or multiple partners in period 2, and syphilis or gonorrhea, taking money or drugs for sex, sex with a sex trade worker, sexual partner who used injection drugs, and sexual partner who was HIV positive in both time periods. Donors coded for PrEP use alone were predominantly male (95% in period 1, 94% in period 2), and younger than other donors (about 38% under 30, vs 16% of all donors).

Conclusions:

The number of donors with deferral codes for PrEP use, either alone or in combination with other risk factor deferrals increased slightly after implementation of sexual risk behaviour criteria, with about 60% of these donors being deferred for answering yes to PrEP use alone.  Given the low rate of deferral, it is possible that individuals who are on PrEP and otherwise eligible for donation are self-deferring. Use of PrEP in the general population is increasing. Therefore, PrEP deferrals may have a greater impact in the future.