CROI 2024 Abstract eBook

Abstract eBook

Poster Abstracts

guidelines were updated to include oral pre-exposure prophylaxis (PrEP) for PBFW, but availability of PrEP for PBFW is still limited in SA health facilities and PrEP discontinuation remains a challenge to effective use in this population. Methods: In an antenatal clinic based in Cape Town, SA, the observational study recruited pregnant women without HIV between Aug 2019–Oct 2021. The study provided HIV testing, counseling and offer of oral PrEP (TDF/FTC) to all pregnant women at their first visit, with follow-up through 12 months postpartum. At quarterly study visits study counselors conducted HIV testing and counselling to monitor serostatus of PBFW. In addition, HIV results, CD4 counts, and viral loads were reviewed for all study participants at the end of follow-up to confirm final serostatuses in electronic patient and laboratory files. We calculated HIV incidence rate using study follow-up person-time of Aug 2019 – Feb 2023. The numerator included seroconversions in study and lab results (incl. lost to follow-up [LTFU]). HIV incidence was stratified by pregnancy and postpartum time, using estimated delivery dates for those who were LTFU. Results: Of the 1195 women enrolled, 1009 (84%) received a PrEP prescription and 82% confirmed PrEP initiation through self-report. After 12 months follow-up, 283 (26%) women continued PrEP use. Overall, 16 women (0.5%) seroconverted over 1684.8 woman-years of follow-up with an HIV incidence rate of 0.95/100 woman-years [95% confidence interval (CI) 0.58–1.55]. Of 16 seroconversions, 1 woman (6%) reported taking PrEP in the past 3 months, 1 (6%) seroconverted during pregnancy, and HIV incidence was higher among women who had stopped or never started PrEP (1.89/100 woman-years vs 0.11/100 woman-years who continued PrEP). In the first 6 months postpartum, HIV incidence was 1.07/100 woman-years [95% CI 0.43–2.22] and 60% of the women seroconverted later in postpartum (>6 months) in 1.12/100 woman years. Conclusion: Despite the high PrEP initiation at enrolment, we observed a high HIV incidence rate in postpartum in women who had started PrEP and discontinued, highlighting the importance of appropriate interventions targeting postdelivery PrEP continuation through integration of PrEP delivery with services such as family planning and baby visits. The Role of Maternal Broadly Neutralizing Antibody Activity in Perinatal Transmission of HIV-1 Krithika P Karthigeyan 1 , Ashley Nelson 1 , Dieter Mielke 2 , Christian Binuya 1 , Ria Goswami 1 , John Isaac 1 , Elena Giorgi 3 , Justin Pollara 2 , Joshua Eudailey 1 , Megan Connors 1 , Carolyn Weinbaum 1 , Genevieve G. Fouda 1 , Feng Gao 2 , Manish Sagar 4 , Sallie Permar 1 1 Weill Cornell Medicine, New York, NY, USA, 2 Duke University, Durham, NC, USA, 3 Fred Hutchinson Cancer Research Center, Seattle, WA, USA, 4 Boston Medical Center, Boston, MA, USA Background: Despite increased availability to antiretroviral therapy (ART), up to 5% of women living with HIV (WLH) still transmit the virus to their infants. While broadly neutralizing antibodies (bNAbs) are the immunologic goal of HIV-1 vaccine candidates, we have demonstrated escape of infant HIV variants in the presence of bNAbs targeting a single, dominant epitope in postnatal transmitters. We hypothesize that WLH with bNAb responses against single epitopes of the HIV envelope are at higher risk of perinatal transmission due to viral escape, and this impacts the development of a bNAb response in infants. Methods: Plasma was acquired around delivery from 15 perinatal transmitters and 47 non-transmitters with HIV from the US-based, pre-ART era Mother Infant Cohort Study (MICS), matched 1:3 on CD4+ T-cell counts, maternal age, delivery type. Plasma from paired infants with HIV was acquired at 1- 3 years of age. Maternal and infant plasma was screened for neutralization against a global HIV-1 panel, with breadth defined as neutralizing ≥ 5 out of 10 viruses with an ID 50 ≥40. For transmitters with breadth, plasma was screened against HIV-1 pseudoviruses with epitope mutations, and a two-fold reduction in neutralization compared to wild-type was considered as mapping to an epitope. Antibody dependent cellular cytotoxicity (ADCC), was assessed against cells infected with a transmitted/founder subtype B virus (WITO).

and safety studies are warranted to evaluate TAF for PrEP in pregnant and postpartum women.

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Video Observed Therapy for Preexposure Prophylaxis Use in South African Pregnant/Postpartum Women Sumaya Dadan 1 , Catherine Orrell 2 , Peter L. Anderson 3 , Catriona Waitt 4 , Saye Khoo 4 , Landon Myer 1 , Dvora L Joseph Davey 5 1 University of Cape Town, Cape Town, South Africa, 2 Desmond Tutu HIV Foundation, Cape Town, South Africa, 3 University of Colorado Anschutz Medical Campus, Aurora, CO, USA, 4 University of Liverpool, Liverpool, United Kingdom, 5 University of California Los Angeles, Los Angeles, CA, USA Background: Daily use of oral PrEP is essential for effectiveness. Video observed therapy (VOT) is an adherence technique involving daily observation of participant dosing via digital means. VOT is an alternative to directly observed therapy and may be useful for resource-scarce settings and pharmacokinetic (PK) studies. This study aims to evaluate the feasibility and acceptability of VOT in a PK study (PrEP PK) of oral PrEP in pregnant and postpartum South African women. Methods: We analyzed data from adult pregnant and postpartum women collected over a year in the PrEP PK study. Each participant was observed for 16 weeks: 8 weeks in pregnancy, 8 weeks postpartum. Feasibility was defined as participant adherence to VOTs, reported as fraction of expected doses observed (FEDO). A median FEDO of ≥85% indicated VOT feasibility while <85% indicated lack of feasibility. Logistic regression analysis was used to determine the impact of baseline characteristics on FEDO score. Linear mixed effect models (LME) were used to examine the effect of observation time and pregnancy state on FEDO score. Acceptability was assessed through semi-structured questionnaires and interviews. Results: Among n=53 women in the study, 39(73.6%) completed all 16 weeks of observation, median(IQR) observation time: 15(14-16) weeks. Mean(SD) age was 28(6) years. Of the 4571 videos expected 4112(90.0%) were received. Reasons for missed videos are in Table 1. Median(IQR) FEDO exceeded the feasibility threshold and was 91.4(82.9-97.1)%. There was no significant impact of baseline characteristics on FEDO score. FEDO increased over weeks of observation: FEDO at week 1(81%); week 7(92%) and week 15(97%). On LME modelling, every additional week of observation time was associated with a 0.5%(95% CI: 0.20%, 0.89%) increase in median FEDO score (p value=0.002). During pregnancy, 94% of expected videos were received; 98% were received postpartum. There was no significant association between pregnancy state and FEDO score in LME modelling (P value= 0.523). When participants were asked about their experiences with VOT, 100% of respondents said that they would do VOTs again and 98% felt that it helped them adhere to PrEP. Conclusion: VOT is feasible and acceptable in pregnant and postpartum women for monitoring and supporting daily PrEP adherence. A high proportion of women successfully completed the observation period. VOT was also a useful technique for assuring daily dosing; and can be applied to future PK studies that require strict adherence. The figure, table, or graphic for this abstract has been removed. PrEP Discontinuation and High HIV Incidence in South African Pregnant and Postpartum Women Rufaro Mvududu 1 , Kalisha Bheemraj 1 , Aurelie Nelson 1 , Linda-Gail Bekker 2 , Thomas Coates 3 , Landon Myer 1 , Dvora L. Joseph Davey 3 1 University of Cape Town, Cape Town, South Africa, 2 Desmond Tutu HIV Foundation, Cape Town, South Africa, 3 University of California Los Angeles, Los Angeles, CA, USA Background: High HIV incidence is a major concern for pregnant and breastfeeding women (PBFW) in South Africa (SA) due to increased risk of HIV acquisition doubling during these periods. In 2019, the SA Department of Health

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