CROI 2023: Epidemiologic Trends and Prevention for HIV and Other Sexually Transmitted Infections.

At the 2023 Conference on Retroviruses and Opportunistic Infections (CROI), several investigators used tests of recent HIV infection to track which populations are currently most heavily impacted by HIV and to estimate HIV infection rates in those populations. Assisted partner notification for HIV was successfully applied for spouses of persons with HIV and sexual and injection partners of people who inject drugs; however, delays in linkage to care were seen for non-spousal partners in one study. Lack of awareness of HIV positive status remains an issue in various populations; several presentations focused on novel strategies for improving HIV testing uptake in these populations. Doxycycline administered as 200 mg post sexual exposure significantly reduced the risk of syphilis, chlamydia, and gonorrhea infection in men who have sex with men but did not prevent bacterial sexually transmitted infections (STIs) in cis-gender women; reasons for this discrepancy are currently being explored. Although oral HIV preexposure prophylaxis (PrEP) is increasingly being used in populations in greatest need of prevention tools, PrEP uptake and persistence remain low in a number of key populations, including people who inject drugs. Several innovative delivery models show early promise in addressing gaps along the PrEP continuum. The successful use of injectable cabotegravir PrEP in several populations was presented at this conference, although uptake remains low globally. The pipeline of novel long-acting and rapid-onset PrEP agents appears to be robust, including implants, vaginal rings, and topical inserts, with several presentations focusing on preclinical and early clinical trials.

Postexposure Doxycycline to Prevent Bacterial Sexually Transmitted Infections.

BACKGROUND: Interventions to reduce sexually transmitted infections (STIs) among men who have sex with men (MSM) are needed. METHODS: We conducted an open-label, randomized study involving MSM and transgender women who were taking preexposure prophylaxis (PrEP) against human immunodeficiency virus (HIV) infection (PrEP cohort) or living with HIV infection (persons living with HIV infection [PLWH] cohort) and who had had Neisseria gonorrhoeae (gonorrhea), Chlamydia trachomatis (chlamydia), or syphilis in the past year. Participants were randomly assigned in a 2:1 ratio to take 200 mg of doxycycline within 72 hours after condomless sex (doxycycline postexposure prophylaxis) or receive standard care without doxycycline. STI testing was performed quarterly. The primary end point was the incidence of at least one STI per follow-up quarter. RESULTS: Of 501 participants (327 in the PrEP cohort and 174 in the PLWH cohort), 67% were White, 7% Black, 11% Asian or Pacific Islander, and 30% Hispanic or Latino. In the PrEP cohort, an STI was diagnosed in 61 of 570 quarterly visits (10.7%) in the doxycycline group and 82 of 257 quarterly visits (31.9%) in the standard-care group, for an absolute difference of -21.2 percentage points and a relative risk of 0.34 (95% confidence interval [CI], 0.24 to 0.46; P<0.001). In the PLWH cohort, an STI was diagnosed in 36 of 305 quarterly visits (11.8%) in the doxycycline group and 39 of 128 quarterly visits (30.5%) in the standard-care group, for an absolute difference of -18.7 percentage points and a relative risk of 0.38 (95% CI, 0.24 to 0.60; P<0.001). The incidences of the three evaluated STIs were lower with doxycycline than with standard care; in the PrEP cohort, the relative risks were 0.45 (95% CI, 0.32 to 0.65) for gonorrhea, 0.12 (95% CI, 0.05 to 0.25) for chlamydia, and 0.13 (95% CI, 0.03 to 0.59) for syphilis, and in the PLWH cohort, the relative risks were 0.43 (95% CI, 0.26 to 0.71), 0.26 (95% CI, 0.12 to 0.57), and 0.23 (95% CI, 0.04 to 1.29), respectively. Five grade 3 adverse events and no serious adverse events were attributed to doxycycline. Of the participants with gonorrhea culture available, tetracycline-resistant gonorrhea occurred in 5 of 13 in the doxycycline groups and 2 of 16 in the standard-care groups. CONCLUSIONS: The combined incidence of gonorrhea, chlamydia, and syphilis was lower by two thirds with doxycycline postexposure prophylaxis than with standard care, a finding that supports its use among MSM with recent bacterial STIs. (Funded by the National Institutes of Health; DoxyPEP ClinicalTrials.gov number, NCT03980223.).

Antiretroviral Drugs for Treatment and Prevention of HIV Infection in Adults: 2022 Recommendations of the International Antiviral Society-USA Panel.

Importance: Recent advances in treatment and prevention of HIV warrant updated recommendations to guide optimal practice. Objective: Based on a critical evaluation of new data, to provide clinicians with recommendations on use of antiretroviral drugs for the treatment and prevention of HIV, laboratory monitoring, care of people aging with HIV, substance use disorder and HIV, and new challenges in people with HIV, including COVID-19 and monkeypox virus infection. Evidence Review: A panel of volunteer expert physician scientists were appointed to update the 2020 consensus recommendations. Relevant evidence in the literature (PubMed and Embase searches, which initially yielded 7891 unique citations, of which 834 were considered relevant) and studies presented at peer-reviewed scientific conferences between January 2020 and October 2022 were considered. Findings: Initiation of antiretroviral therapy (ART) is recommended as soon as possible after diagnosis of HIV. Barriers to care should be addressed, including ensuring access to ART and adherence support. Integrase strand transfer inhibitor-containing regimens remain the mainstay of initial therapy. For people who have achieved viral suppression with a daily oral regimen, long-acting injectable therapy with cabotegravir plus rilpivirine given as infrequently as every 2 months is now an option. Weight gain and metabolic complications have been linked to certain antiretroviral medications; novel strategies to ameliorate these complications are needed. Management of comorbidities throughout the life span is increasingly important, because people with HIV are living longer and confronting the health challenges of aging. In addition, management of substance use disorder in people with HIV requires an evidence-based, integrated approach. Options for preexposure prophylaxis include oral medications (tenofovir disoproxil fumarate or tenofovir alafenamide plus emtricitabine) and, for the first time, a long-acting injectable agent, cabotegravir. Recent global health emergencies, like the SARS-CoV-2 pandemic and monkeypox virus outbreak, continue to have a major effect on people with HIV and the delivery of services. To address these and other challenges, an equity-based approach is essential. Conclusions and Relevance: Advances in treatment and prevention of HIV continue to improve outcomes, but challenges and opportunities remain.

Randomized Controlled Trial of Automated Directly Observed Therapy for Measurement and Support of PrEP Adherence Among Young Men Who have Sex with Men.

Measurement of adherence to oral pre-exposure prophylaxis (PrEP) in real-time has been challenging. We developed DOT Diary, a smartphone application that combines automated directly observed therapy with a PrEP adherence visualization toolkit, and tested its ability to measure PrEP adherence and to increase adherence among a diverse cohort of young men who have sex with men (MSM). We enrolled 100 MSM in San Francisco and Atlanta and randomly assigned them 2:1 to DOT Diary versus standard of care. Concordance between DOT Diary measurement and drug levels in dried blood spots was substantial, with 91.0% and 85.3% concordance between DOT Diary and emtricitabine-triphosphate and tenofovir-diphosphate, respectively. There was no significant difference in the proportion of participants with detectable PrEP drug levels at 24 weeks between study arms. These results suggest DOT Diary is substantially better than self-reported measures of adherence, but additional interventions are needed to improve PrEP adherence over time.

RESUMEN: La medición de la adherencia a la profilaxis oral previa a la exposición (PrEP) en tiempo real ha constituido un desafío. Hemos desarrollado DOT Diary, una aplicación para teléfonos inteligentes que combina la terapia automatizada observada de forma directa con un kit de herramientas para visualizar la adherencia a la PrEP, y testeamos su capacidad para medir la adherencia a la PrEP, así como para aumentar la adherencia entre una cohorte variada de hombres jóvenes que tienen sexo con hombres (HSH). Reclutamos a 100 HSH en San Francisco y Atlanta y los asignamos aleatoriamente 2:1 a DOT Diary con respecto a la asistencia estándar. La concordancia entre la medición del DOT Diary y los niveles de fármacos en gotas de sangre seca fue sustancial, con un 91,0% y un 85,3% de concordancia entre el uso del DOT Diary y el de emtricitabina-trifosfato y tenofovir-difosfato, respectivamente. No hubo diferencias significativas en la proporción de participantes con niveles detectables del fármaco de la PrEP a las 24 semanas entre los brazos del estudio. Estos resultados sugieren que DOT Diary es sustancialmente superior a las medidas de adherencia que se notifican de forma personal, aunque hacen falta intervenciones adicionales para mejorar la adherencia a la PrEP a largo plazo.

Baseline host determinants of robust human HIV-1 vaccine-induced immune responses: A meta-analysis of 26 vaccine regimens.

BACKGROUND: The identification of baseline host determinants that associate with robust HIV-1 vaccine-induced immune responses could aid HIV-1 vaccine development. We aimed to assess both the collective and relative performance of baseline characteristics in classifying individual participants in nine different Phase 1-2 HIV-1 vaccine clinical trials (26 vaccine regimens, conducted in Africa and in the Americas) as High HIV-1 vaccine responders. METHODS: This was a meta-analysis of individual participant data, with studies chosen based on participant-level (vs. study-level summary) data availability within the HIV-1 Vaccine Trials Network. We assessed the performance of 25 baseline characteristics (demographics, safety haematological measurements, vital signs, assay background measurements) and estimated the relative importance of each characteristic in classifying 831 participants as High (defined as within the top 25th percentile among positive responders or above the assay upper limit of quantification) versus Non-High responders. Immune response outcomes included HIV-1-specific serum IgG binding antibodies and Env-specific CD4+ T-cell responses assessed two weeks post-last dose, all measured at central HVTN laboratories. Three variable importance approaches based on SuperLearner ensemble machine learning were considered. FINDINGS: Overall, 30.1%, 50.5%, 36.2%, and 13.9% of participants were categorized as High responders for gp120 IgG, gp140 IgG, gp41 IgG, and Env-specific CD4+ T-cell vaccine-induced responses, respectively. When including all baseline characteristics, moderate performance was achieved for the classification of High responder status for the binding antibody responses, with cross-validated areas under the ROC curve (CV-AUC) of 0.72 (95% CI: 0.68, 0.76) for gp120 IgG, 0.73 (0.69, 0.76) for gp140 IgG, and 0.67 (95% CI: 0.63, 0.72) for gp41 IgG. In contrast, the collection of all baseline characteristics yielded little improvement over chance for predicting High Env-specific CD4+ T-cell responses [CV-AUC: 0.53 (0.48, 0.58)]. While estimated variable importance patterns differed across the three approaches, female sex assigned at birth, lower height, and higher total white blood cell count emerged as significant predictors of High responder status across multiple immune response outcomes using Approach 1. Of these three baseline variables, total white blood cell count ranked highly across all three approaches for predicting vaccine-induced gp41 and gp140 High responder status. INTERPRETATION: The identified features should be studied further in pursuit of intervention strategies to improve vaccine responses and may be adjusted for in analyses of immune response data to enhance statistical power. FUNDING: National Institute of Allergy and Infectious Diseases (UM1AI068635 to YH, UM1AI068614 to GDT, UM1AI068618 to MJM, and UM1 AI069511 to MCK), the Duke CFAR P30 AI064518 to GDT, and National Institute of Dental and Craniofacial Research (R01DE027245 to JJK). This work was also supported by the Bill and Melinda Gates Foundation. The content is solely the responsibility of the authors and does not necessarily represent the official views of any of the funding sources.

Effect of Social Determinants of Health on Uncontrolled Human Immunodeficiency Virus (HIV) Infection Among Persons With HIV in San Francisco, California.

Background: In 2010-2014, the San Francisco Department of Public Health (SFDPH) established programs to rapidly link people with human immunodeficiency virus (PWH) to care and offer antiretroviral therapy (ART) at human immunodeficiency virus (HIV) diagnosis. Such programs reduced the number of PWH out of care or with detectable HIV viral load (ie, uncontrolled HIV infection). We investigated the role of social determinants of health (SDH) on uncontrolled HIV. Methods: Cross-sectional data from adult PWH diagnosed and reported to the SFDPH as of December 31, 2019, prescribed ART, and with confirmed San Francisco residency during 2017-2019 were analyzed in conjunction with SDH metrics derived from the American Community Survey 2015-2019. We focused on 5 census tract-level SDH metrics: percentage of residents below the federal poverty level, with less than a high school diploma, or uninsured; median household income; and Gini index. We compared uncontrolled HIV prevalence odds ratios (PORs) across quartiles of each metric independently using logistic regression models. Results: The analysis included 7486 PWH (6889 controlled HIV; 597 uncontrolled HIV). Unadjusted PORs of uncontrolled HIV rose with increasingly marginalized quartiles, compared to the least marginalized quartile for each metric. Adjusting for demographics and transmission category, the POR for uncontrolled HIV for PWH in the most marginalized quartile remained significant across metrics for poverty (POR = 2.0; confidence interval [CI] = 1.5-2.6), education (POR = 2.4; CI = 1.8-3.2), insurance (POR = 1.8; CI = 1.3-2.5), income (POR = 1.8; CI = 1.4-2.3), and income inequality (POR = 1.5; CI = 1.1-2.0). Conclusions: Beyond demographics, SDH differentially affected the ability of PWH to control HIV. Despite established care programs, PWH experiencing socioeconomic marginalization require additional support to achieve health outcome goals.

Impact of Multicomponent Support Strategies on Human Immunodeficiency Virus Virologic Suppression Rates During Coronavirus Disease 2019: An Interrupted Time Series Analysis.

BACKGROUND: After coronavirus disease 2019 (COVID-19) shelter-in-place (SIP) orders, viral suppression (VS) rates initially decreased within a safety-net human immunodeficiency virus (HIV) clinic in San Francisco, particularly among people living with HIV (PLWH) who are experiencing homelessness. We sought to determine if proactive outreach to provide social services, scaling up of in-person visits, and expansion of housing programs could reverse this decline. METHODS: We assessed VS 24 months before and 13 months after SIP using mixed-effects logistic regression followed by interrupted time series (ITS) analysis to examine changes in the rate of VS per month. Loss to follow-up (LTFU) was assessed via active clinic tracing. RESULTS: Data from 1816 patients were included; the median age was 51 years, 12% were female, and 14% were experiencing unstable housing/homelessness. The adjusted odds of VS increased 1.34 fold following institution of the multicomponent strategies (95% confidence interval [CI], 1.21-1.46). In the ITS analysis, the odds of VS continuously increased 1.05 fold per month over the post-intervention period (95% CI, 1.01-1.08). Among PLWH who previously experienced homelessness and successfully received housing support, the odds of VS were 1.94-fold higher (95% CI, 1.05-3.59). The 1-year LTFU rate was 2.8 per 100 person-years (95% CI, 2.2-3.5). CONCLUSIONS: The VS rate increased following institution of the multicomponent strategies, with a lower LFTU rate compared with prior years. Maintaining in-person care for underserved patients, with flexible telemedicine options, along with provision of social services and permanent expansion of housing programs, will be needed to support VS among underserved populations during the COVID-19 pandemic.

SARS-CoV-2 incidence, testing rates, and severe COVID-19 outcomes among people with and without HIV.

To assess SARS-CoV-2 outcomes, we matched a municipal COVID-19 registry and clinic rosters from a municipal primary care network containing a large HIV clinic and assessed clinical outcomes by HIV status. The risk of severe COVID-19 was higher among people with HIV (PWH, adjusted relative risk = 1.84, 95% confidence interval = 1.05-3.25), while SARS-CoV-2 incidence was lower despite higher testing rates. SARS-CoV-2 vaccination campaigns should prioritize PWH to prevent severe COVID-19 disease given potentially higher risk.

Development of a Citywide Rapid Antiretroviral Therapy Initiative in San Francisco.

INTRODUCTION: Ending the HIV epidemic in the U.S. holds rapid antiretroviral therapy as a key strategy to improve the health of those with HIV and to decrease transmission. In 2015, Getting to Zero San Francisco, a multisector consortium, expanded rapid antiretroviral therapy citywide. METHODS: A Getting to Zero San Francisco Rapid ART Program Initiative for HIV Diagnoses Committee (academic, community, service delivery, health department partners) designed the program, protocol, dissemination plan, and monitoring strategy. Newly diagnosed patients were linked to an HIV medical home or Rapid ART Program Initiative for HIV Diagnoses initiation hub to best deliver rapid antiretroviral therapy across a diverse patient mix, with a goal of ≤5 working days from diagnosis to care and ≤1 day from care to antiretroviral therapy. Stakeholders were trained on rapid antiretroviral therapy via Getting to Zero San Francisco meetings, in-services, public health detailing, and peer-to-peer recruiting, prioritizing HIV clinics serving patients of color, Latinx ethnicity, youth, and the uninsured or publicly insured. Rapid ART Program Initiative for HIV Diagnoses-specific metrics were derived from surveillance data; stratified by sex/gender, age, race/ethnicity, and housing status; and presented at public meetings. Data were analyzed between January and April 2021. RESULTS: From 2014 to 2018, median time from diagnosis to care decreased 71% (7 to 2 days), care to antiretroviral therapy decreased from 19 to 0 days, and diagnosis to virologic suppression decreased 51% (94 to 46 days). Improvements occurred regardless of age, race/ethnicity, sex/gender, exposure, or housing status. CONCLUSIONS: During a citywide initiative to optimize antiretroviral therapy initiation, time from HIV diagnosis to care, antiretroviral therapy, and virologic suppression decreased across all affected groups to varying degrees. The Rapid ART Program Initiative for HIV Diagnoses Committee continues to address challenges to retention and expand implementation.

Sensitivity and Specificity of the National Death Index for Multiple Causes of Death in People With HIV.

OBJECTIVES: Inaccuracies in cause-of-death information in death certificates can reduce the validity of national death statistics and result in poor targeting of resources to reduce morbidity and mortality in people with HIV. Our objective was to measure the sensitivity, specificity, and agreement between multiple causes of deaths from death certificates obtained from the National Death Index (NDI) and causes determined by expert physician review. METHODS: Physician specialists determined the cause of death using information collected from the medical records of 50 randomly selected HIV-infected people who died in San Francisco from July 1, 2016, through May 31, 2017. Using expert review as the gold standard, we measured sensitivity, specificity, and agreement. RESULTS: The NDI had a sensitivity of 53.9% and a specificity of 66.7% for HIV deaths. The NDI had a moderate sensitivity for non-AIDS-related infectious diseases and non-AIDS-related cancers (70.6% and 75.0%, respectively) and high specificity for these causes (100.0% and 94.7%, respectively). The NDI had low sensitivity and high specificity for substance abuse (27.3% and 100.0%, respectively), heart disease (58.3% and 86.8%, respectively), hepatitis B/C (33.3% and 97.7%, respectively), and mental illness (50.0% and 97.8%, respectively). The measure of agreement between expert review and the NDI was lowest for HIV (κ = 0.20); moderate for heart disease (κ = 0.45) and hepatitis B/C (κ = 0.40); high for non-AIDS-related infectious diseases (κ = 0.76) and non-AIDS-related cancers (κ = 0.72); and low for all other causes of death (κ < 0.35). CONCLUSIONS: Our findings support education and training of health care providers to improve the accuracy of cause-of-death information on death certificates.

HLA tapasin independence: broader peptide repertoire and HIV control.

Human leukocyte antigen (HLA) class I allotypes vary in their ability to present peptides in the absence of tapasin, an essential component of the peptide loading complex. We quantified tapasin dependence of all allotypes that are common in European and African Americans (n = 97), which revealed a broad continuum of values. Ex vivo examination of cytotoxic T cell responses to the entire HIV-1 proteome from infected subjects indicates that tapasin-dependent allotypes present a more limited set of distinct peptides than do tapasin-independent allotypes, data supported by computational predictions. This suggests that variation in tapasin dependence may impact the strength of the immune responses by altering peptide repertoire size. In support of this model, we observed that individuals carrying HLA class I genotypes characterized by greater tapasin independence progress more slowly to AIDS and maintain lower viral loads, presumably due to increased breadth of peptide presentation. Thus, tapasin dependence level, like HLA zygosity, may serve as a means to restrict or expand breadth of the HLA-I peptide repertoire across humans, ultimately influencing immune responses to pathogens and vaccines.

Antiretroviral Drugs for Treatment and Prevention of HIV Infection in Adults: 2020 Recommendations of the International Antiviral Society-USA Panel.

Importance: Data on the use of antiretroviral drugs, including new drugs and formulations, for the treatment and prevention of HIV infection continue to guide optimal practices. Objective: To evaluate new data and incorporate them into current recommendations for initiating HIV therapy, monitoring individuals starting on therapy, changing regimens, preventing HIV infection for those at risk, and special considerations for older people with HIV. Evidence Review: New evidence was collected since the previous International Antiviral (formerly AIDS) Society-USA recommendations in 2018, including data published or presented at peer-reviewed scientific conferences through August 22, 2020. A volunteer panel of 15 experts in HIV research and patient care considered these data and updated previous recommendations. Findings: From 5316 citations about antiretroviral drugs identified, 549 were included to form the evidence basis for these recommendations. Antiretroviral therapy is recommended as soon as possible for all individuals with HIV who have detectable viremia. Most patients can start with a 3-drug regimen or now a 2-drug regimen, which includes an integrase strand transfer inhibitor. Effective options are available for patients who may be pregnant, those who have specific clinical conditions, such as kidney, liver, or cardiovascular disease, those who have opportunistic diseases, or those who have health care access issues. Recommended for the first time, a long-acting antiretroviral regimen injected once every 4 weeks for treatment or every 8 weeks pending approval by regulatory bodies and availability. For individuals at risk for HIV, preexposure prophylaxis with an oral regimen is recommended or, pending approval by regulatory bodies and availability, with a long-acting injection given every 8 weeks. Monitoring before and during therapy for effectiveness and safety is recommended. Switching therapy for virological failure is relatively rare at this time, and the recommendations for switching therapies for convenience and for other reasons are included. With the survival benefits provided by therapy, recommendations are made for older individuals with HIV. The current coronavirus disease 2019 pandemic poses particular challenges for HIV research, care, and efforts to end the HIV epidemic. Conclusion and Relevance: Advances in HIV prevention and management with antiretroviral drugs continue to improve clinical care and outcomes among individuals at risk for and with HIV.

Virtual CROI 2020: Highlights of Epidemiology, Public Health, and Prevention Research.

At the 2020 Conference on Retroviruses and Opportunistic Infections, held virtually as a result of the emerging COVID-19 pandemic, trends in the HIV epidemic were highlighted, with decreasing HIV incidence reported across several countries, although key regions remain heavily impacted, including the US South. Adolescent girls and young women, men who have sex with men (MSM), transgender persons, and people who inject drugs continue to experience a high burden of new infections. Sexually transmitted infections during pregnancy can lead to a number of adverse outcomes in infants; novel strategies to detect and treat these infections are needed. Innovative HIV testing strategies, including self-testing and assisted partner services, are expanding the reach of testing; however, linkage to care can be improved. Novel preexposure prophylaxis (PrEP) delivery strategies are increasing uptake of PrEP in different groups, although adherence and persistence remain a challenge. Use of on-demand PrEP is increasing among MSM in the US. Strategies are needed to address barriers to PrEP uptake and persistence among cis- and transgender women. Several novel regimens for postexposure prophylaxis show promise.

Impact of vaccine type on HIV-1 vaccine elicited antibody durability and B cell gene signature.

Efficacious HIV-1 vaccination requires elicitation of long-lived antibody responses. However, our understanding of how different vaccine types elicit durable antibody responses is lacking. To assess the impact of vaccine type on antibody responses, we measured IgG isotypes against four consensus HIV antigens from 2 weeks to 10 years post HIV-1 vaccination and used mixed effects models to estimate half-life of responses in four human clinical trials. Compared to protein-boosted regimens, half-lives of gp120-specific antibodies were longer but peak magnitudes were lower in Modified Vaccinia Ankara (MVA)-boosted regimens. Furthermore, gp120-specific B cell transcriptomics from MVA-boosted and protein-boosted vaccines revealed a distinct signature at a peak (2 weeks after last vaccination) including CD19, CD40, and FCRL2-5 activation along with increased B cell receptor signaling. Additional analysis revealed contributions of RIG-I-like receptor pathway and genes such as SMAD5 and IL-32 to antibody durability. Thus, this study provides novel insights into vaccine induced antibody durability and B-cell receptor signaling.

Missed opportunities to prevent HIV infections among pre-exposure prophylaxis users: a population-based mixed methods study, San Francisco, United States.

INTRODUCTION: Pre-exposure prophylaxis (PrEP) is highly effective, although PrEP adherence and persistence has been variable during real world implementation. Little is known about missed opportunities to enhance PrEP adherence among individuals who later HIV seroconverted after using PrEP. The goal of this analysis was to identify all HIV infections among individuals who had accessed PrEP in an integrated health system in San Francisco, and to identify potentially intervenable factors that could have prevented HIV infection through in-depth interviews with people who HIV seroconverted after using PrEP. METHODS: We identified individuals who initiated PrEP in an integrated safety-net public health system and performed in-depth chart review to determine person-time on and after stopping PrEP over six years. We identified all PrEP seroconversions using the Centers for Disease Control and Prevention's Enhanced HIV/AIDS Reporting System and then calculated HIV incidence while using PrEP and during gaps in use. We then performed in-depth interviews with those who seroconverted. RESULTS: Overall, 986 initiated PrEP across the San Francisco Department of Public Health from July 2012 to November 2018. Data were gathered from 895 person-years on PrEP and 953 after stopping PrEP. The HIV incidence was 7.5-fold higher after stopping PrEP compared to while on PrEP (95% CI 1 to 336). Of the eight individuals who HIV seroconverted; only one was taking PrEP at the time of seroconversion but was using on-demand PrEP inconsistently. All eight agreed to qualitative interviews. Major barriers to PrEP persistence included substance use, mental health and housing loss; difficulty accessing PrEP due to cost, insurance, and the cost and time of medical visits; difficulty weighing PrEP's benefit versus self-perceived risk; and entering a primary partnership. The individual who developed HIV using on-demand PrEP reported confusion about the dosing regimen and which sexual encounters required accompanying PrEP dosing. CONCLUSIONS: HIV incidence during gaps in PrEP use was nearly eight-fold higher than while on PrEP in this large cohort in San Francisco. Many individuals who stop PrEP remain at risk of HIV, and participants reported that proactive outreach could potentially have prevented HIV infections. Individuals using non-daily PrEP may require additional education and support in the United States.

Understanding PrEP Persistence: Provider and Patient Perspectives.

PrEP persistence, or PrEP use over time, has been shown to be short, with most PrEP users stopping within 6-12 months. Furthermore, those most vulnerable to HIV often use PrEP for shorter periods. This qualitative study explores patient, provider, and contextual factors that influence PrEP persistence. In interviews with 25 PrEP users and 18 PrEP providers in San Francisco's safety net clinics, we analyze the perceived benefits and difficulties of taking PrEP, including structural barriers. We identify different steps in receipt of PrEP care (clinic visits and lab tests, pharmacy interactions, and medication adherence), and describe barriers and facilitators for providers and patients at each step. Our findings suggest that drop-in visits, streamlined testing, standing orders for labs, and 90-day PrEP prescriptions are highly desirable for many PrEP users. Also important are the proactive provision of adherence support and counseling, and referrals for housing, substance use, and mental health services.