High prevalence of human papillomavirus (HPV) in unvaccinated adolescent girls in South Africa, particularly those living with HIV.

INTRODUCTION: In 2014, South Africa implemented a national two-dose HPV vaccination programme using the bivalent vaccine for girls aged 9 years and older attending Grade 4 at public schools. We assessed HPV prevalence and risk factors among South African adolescent girls and young women (AGYW) aged 17-18 years who were ineligible for vaccination. METHODS: From June to December 2019, we surveyed AGYW aged 17-18 years attending primary care clinics in four South African provinces. Consenting participants completed a questionnaire, underwent HIV counselling and testing, and self-collected a vaginal swab for HPV testing. Samples were tested by Seegene AnyPlex™ II HPV28. We used summary statistics to describe the population characteristics and logistic regression to examine the association between risk factors and high-risk HPV detection. RESULTS: 910 participants were screened, 900 enrolled, 896 had valid HPV results, and 819 were unvaccinated and included in this study. Of these, 248 (30.3 %) were living with HIV and 597 (72.9 %) reported ever having vaginal sex. Overall, 463 (56.5 %) had at least one high-risk HPV detected, and 177 (21.6 %) had HPV16/18 detected. AGYW living with HIV had a higher prevalence of any high-risk HPV (65.3 % vs 52.7 %, p < 0.001) and HPV 16/18 (29.4 % vs 18.2 %, p < 0.001) compared to those without HIV. Multiple infections were also more common in participants living with HIV, with three or more high-risk HPV types detected in 32.3 % compared with 15.4 % of those without HIV (p < 0.001). In multivariate analyses, HIV status (p < 0.001) and higher number of lifetime sexual partners (p-trend<0.001) were associated with high-risk HPV detection. CONCLUSIONS: High-risk HPV was very common in unvaccinated South Africa AGYW, especially among those living with HIV, highlighting the importance of HPV vaccination in settings with high HIV prevalence.

Hoping to Adhere? Examining the Relationship Between Hope and Pre-exposure Prophylaxis Willingness, Adherence, and Persistence Among Young Women in South Africa and Zimbabwe (HPTN 082).

Hope is a powerful psychological construct which is linked to positive health. Greater hope is associated with improved antiretroviral therapy adherence; however, less is known about the impact of hope on oral pre-exposure prophylaxis (PrEP) outcomes. HIV Prevention Trials Network 082, was an open-label PrEP study among young women (ages 16-25) in South Africa and Zimbabwe. Hope was measured at baseline and follow-up using a subset of the Hope for the Future Scale (score range 6-24) and PrEP willingness was measured using a subscale of the HIV Prevention Readiness Measure (score range 6-30). Intracellular tenofovir-diphosphate (TFV-DP) concentrations were obtained from dried blood spot samples at weeks 13, 26, and 52; high PrEP adherence was defined as TFV-DP concentrations ≥ 700 fmol/punch. Persistence was defined as TFV-DP > 16 fmol/punch at weeks 26 and 52. Linear regression and generalized estimating equations were used to assess the relationship between hope and PrEP willingness, adherence, and persistence. The median age of participants (n = 432) was 21 years (interquartile range [IQR]: 19-22). The mean hope score at baseline was 21.0 (SD = 3.4). Although hope was positively associated with PrEP willingness (ß = 0.22, 95% CI 0.15, 0.37), it was not associated with high PrEP adherence (aRR = 1.00, 95% CI 0.96, 1.05), or persistence at follow-up (aRR = 1.02, 95% CI 0.99, 1.05). While cultivating hope may be an important strategy in building willingness to take oral PrEP, it may not be enough to sustain PrEP adherence or persistence.

HIV DNA Levels in Persons Who Acquired HIV in the Setting of Long-Acting Cabotegravir for HIV Prevention: Analysis of Cases from HPTN 083 and 084.

We evaluated HIV DNA levels in individuals who received long-acting cabotegravir (CAB-LA) or tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) pre-exposure prophylaxis in the HPTN 083 and 084 trials and had HIV DNA testing performed to help determine HIV status. HIV DNA testing was performed using peripheral blood mononuclear cell (PBMC) samples collected after a reactive HIV test was obtained at a study site. DNA was quantified using droplet digital PCR (lower limit of detection [LLOD]: 4.09 copies/million PBMCs). Final HIV status and the timing of the first HIV-positive visit were determined by an independent adjudication committee based on HIV test results from real-time site testing and retrospective testing at a centralized laboratory. HIV DNA testing was performed for 133 participants [21 HIV-positive (7 CAB-LA arm, 14 TDF/FTC arm) and 112 HIV-negative; 1-6 tests/person]. For persons with HIV, the time between the first HIV-positive visit and collection of the first sample for DNA testing was a median of 81 days for those receiving CAB-LA (range 41-246) and 11 days for those receiving TDF/FTC (range 3-127). Four (57.1%) of the seven CAB-LA cases with infection had a low initial DNA result [three detected

Preferences for oral and injectable PrEP among qualitative sub-study participants in HPTN 084.

BACKGROUND: HPTN 084 compared the safety and efficacy of long-acting injectable cabotegravir (CAB) to daily oral TDF/FTC for prevention of HIV-1 in uninfected African women. Like a similar trial in MSM/TGW (HPTN 083), the trial was stopped early for efficacy, expediting the need to consider introduction strategies for different populations. We examine survey and qualitative data from a four-country sub-study to examine oral and injectable PrEP acceptability and considerations for CAB access among African women. METHODS: Participants completed baseline and follow-up surveys on HIV risk perception, sexual behavior. product acceptability and adherence during the blinded trial. Additionally, up to two in-depth interviews each with 73 sub-study participants explored product use and trial-related experiences, during the blinded and unblinded study periods. Using survey data, we classified participants as: engaged in female sex work (FSW), having multiple non-transactional partners, or monogamous. A study statistician identified participants' assigned study arm. We followed a thematic analysis process to read transcripts, develop a codebook and apply codes in NVivo to transcripts with intermittent intercoder reliability checks; using Excel matrices to explore differences across risk categories and study arms. FINDINGS: Participants overwhelmingly preferred injections to pills, appreciating the ease, convenience, and privacy of a long-acting formulation. Many participants described challenges with contraceptive and/or study pill adherence, impeded by late night work, unexpected travel, or heavy drinking. Women in the TDF/FTC arm were more likely to describe side effects, compared to those in the CAB arm. Pain also varied widely by study arm. When considering post-trial access to CAB, limited PrEP knowledge, cost and concerns around stigma and poor service quality were potential access barriers. CONCLUSION: Women's desire for privacy and ease of use outweighed injectable concerns, resulting in a strong preference for CAB. Cost and accessibility will need to be addressed by implementation programs.

Pharmacologic evaluation of delayed long-acting cabotegravir administration among cisgender women in HPTN 084.

HPTN 084 demonstrated the superiority of long-acting injectable cabotegravir (CAB-LA) compared with daily oral tenofovir disoproxil fumarate-emtricitabine (F/TDF) for HIV prevention in women. CAB-LA (600 mg) or placebo injections were administered 4 weeks after an initial dose (loading dose) and every 2 months (Q2M) thereafter; this is the approved regimen. Participants experienced both loading dose and Q2M delays during the trial. CAB concentrations were evaluated before a delay, at the visit associated with the delay, and the visit after a delayed injection was administered. During the blinded phase of the trial, 194 participants randomized to CAB-LA experienced at least one injection delay. Plasma CAB concentrations were maintained above the 4× protein adjusted 90% inhibitory concentration (4× PA-IC90; protocol-specific threshold) for all loading dose and 98% of Q2M delays when injections were administered up to 6 weeks late. The feasibility of shifting to an every 3-month (Q3M) regimen in females was interrogated via simulation studies using a population pharmacokinetic model. Q3M injections in both CAB-naïve (with a loading dose) and previously CAB-exposed females were predicted to yield higher steady-state exposures than in males on the approved Q2M regimen. Although there is observed forgiveness following an isolated delayed CAB-LA injection and simulations suggest acceptable CAB-LA exposures in women with a 600 mg CAB-LA Q3M regimen, empirical efficacy of this regimen has not been established, and transitioning to this dosing schema is not recommended. Future pharmacokinetic bridging studies are aimed at evaluating higher dose CAB-LA formulations administered less frequently. CLINICAL TRIALS: This study is registered with ClinicalTrials.gov as NCT03164564.

Integrating a mental health intervention into PrEP services for South African young women: a human-centred implementation research approach to intervention development.

INTRODUCTION: Adolescent girls and young women (AGYW) who may benefit from HIV pre-exposure prophylaxis (PrEP) face high levels of common mental disorders (e.g. depression, anxiety). Common mental disorders can reduce PrEP adherence and increase HIV risk, yet mental health interventions have not been well-integrated into PrEP delivery. METHODS: We conducted a four-phase human-centred design process, from December 2020 to April 2022, to understand mental health challenges among AGYW in Johannesburg, South Africa and barriers to integrated mental health and PrEP services. In the "Discover" phase, we conducted in-depth interviews with AGYW and key informants (KIs) in Johannesburg. We conducted a rapid qualitative analysis, informed by the Consolidated Framework for Implementation Research (CFIR), to identify facilitators and barriers of integrated mental health and PrEP services and mapped barriers to potential implementation strategies. In the "Design" and "Build" phases, we conducted stakeholder workshops to iteratively adapt an evidence-based mental health intervention, the Friendship Bench, and refine implementation strategies for South African PrEP delivery settings. In the "Test" phase, we piloted our adapted Friendship Bench package. RESULTS: Interviews with 70 Discover phase participants (48 AGYW, 22 KIs) revealed the importance of integrated mental health and PrEP services for South African AGYW. Interviewees described barriers and implementation strategies for mental health and PrEP services around the CFIR domains: intervention characteristics (e.g. challenges with AGYW "opening up"); outer Johannesburg setting (e.g. community stigma); inner clinic setting (e.g. judgemental healthcare providers); characteristics of counsellors (e.g. training gaps); and the implementation process (e.g. need for demand creation). The Design and Build workshops included 13 AGYW and 15 KIs. Implementation barriers related to the quality and accessibility of public-sector clinic services, lay counsellor training, and community education and demand creation activities were prioritized. This led to 12 key Friendship Bench adaptations and the specification of 10 implementation strategies that were acceptable and feasible in initial pilot testing with three AGYW. CONCLUSIONS: Using a human-centred approach, we identified determinants and potential solutions for integrating mental health interventions within PrEP services for South African AGYW. This design process centred stakeholders' perspectives, enabling rapid development of an adapted Friendship Bench intervention implementation package.

Vaccine value profile for herpes simplex virus.

Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) are chronic, highly prevalent viral infections that cause significant morbidity around the world. HSV-2 is sexually transmitted and is the leading cause of genital ulcer disease (GUD). It also increases the risk of HIV acquisition, fueling the HIV epidemic. HSV-1 is typically acquired in childhood through nonsexual contact and contributes to oral and ocular disease, but it can also be sexually transmitted to cause GUD. Both HSV-1 and HSV-2 cause neonatal herpes and neurologic disease. Given the ubiquitous nature of HSV-1 and HSV-2 infections and the limited existing prevention and control measures, vaccination would be the most efficient strategy to reduce the global burden of morbidity related to HSV infection. Vaccine strategies include prophylactic vaccination, which would prevent infection among susceptible persons and would likely be given to adolescents, and therapeutic vaccinations, which would be given to people with symptomatic genital HSV-2 infection. This document discusses the vaccine value profile of both types of vaccines. This 'Vaccine Value Profile' (VVP) for HSV is intended to provide a high-level, holistic assessment of the information and data that are currently available to inform the potential public health, economic and societal value of pipeline vaccines and vaccine-like products. This VVP was developed by subject matter experts from academia, non-profit organizations, government agencies and multi-lateral organizations. All contributors have extensive expertise on various elements of the HSV VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information.

Long-acting cabotegravir pharmacokinetics with and without oral lead-in for HIV PrEP.

Long-acting cabotegravir is approved for pre-exposure prophylaxis and combination HIV treatment, both initiated with optional short-term oral lead-in (OLI). We evaluated the impact of OLI on long-acting cabotegravir pharmacokinetics. Cabotegravir plasma concentrations were compared between HIV-positive participants initiating injections with (n = 278) or without (n = 110) OLI in phase III treatment study FLAIR and in HIV-negative participants using OLI (n = 263) in pivotal pre-exposure prophylaxis studies HPTN 083 and HPTN 084. Cabotegravir pharmacokinetic profiles were simulated in three populations (assigned-male-at-birth, 50%-assigned-female-at-birth, and assigned-female-at-birth) under three scenarios: first injection given (A) 1 or (B) 3 days after final OLI dose (OLI-injection gap) or (C) without OLI. The PK objective was 80% of participants achieving 4× in vitro protein-adjusted 90% maximal inhibitory concentration (PA-IC90) and 50% achieving 8× PA-IC90. Observed trough concentrations (Cτ) were similar with and without OLI (P > 0.3). With a 3-day OLI-injection gap, simulated pre-injection Cτ remained above PK objective. Approximately 1-2 weeks after the first injection, simulated PK profiles became nearly identical among all scenarios. Without OLI, it was predicted that 80% of participants achieve 4× PA-IC90 in 1.2, 1.8, and 2.8 days after the first injection in each population, respectively, and 50% achieve 8× PA-IC90 in 1.4, 2.1, and 3.8 days, respectively. Observed long-acting cabotegravir exposure was similar with or without OLI, supporting optional OLI use. Cabotegravir exposure was predicted to remain above PK objective for OLI-injection gaps of ≤3 days and rapidly achieve PK objective after first injection without OLI. Findings are consistent between assigned-male-at-birth and assigned-female-at-birth populations.This study is registered with ClinicalTrials.gov as NCT02720094.

The potential benefits of long-acting injectable cabotegravir in pregnant and breastfeeding women and their infants.

BACKGROUND: Pregnant and breastfeeding women (PBW) in sub-Saharan Africa have high HIV incidence rates and associated risk of vertical transmission to their infants. Oral preexposure prophylaxis (PrEP) and injectable PrEP (long-acting cabotegravir, or CAB-LA) can potentially reduce this HIV transmission, but population-level impacts are uncertain. METHODS: We extended a previously developed model of HIV and PrEP in South Africa to allow for variable PrEP duration and preference in PBW. We considered three potential scenarios for PrEP provision to PBW: oral PrEP only, CAB-LA only, and allowing oral/CAB-LA choice, with uptake and retention assumptions informed by South African data, each compared with a 'base' scenario without PrEP for PBW. RESULTS: Without PrEP for PBW, the model estimates 1.31 million new infections will occur between 2025 and 2035 in South African adults and children, including 100 000 in PBW, 16 800 in infants at/before birth, and 35 200 in children through breastmilk. In the oral PrEP-only scenario, these numbers would reduce by 1.2% (95% CI: 0.7-1.7%), 8.6% (4.8-12.9%), 4.0% (2.1-5.8%), and 5.3% (3.0-8.2%) respectively. In the CAB-LA-only scenario, the corresponding reductions would be 6.1% (2.9-9.6%), 41.2% (19.8-65.0%), 12.6% (6.0-19.4%), and 29.5% (13.9-46.8%), respectively, and in the oral/CAB-LA choice scenario, similar reductions would be achieved [5.6% (3.4-8.0%), 39% (23.4-55.9%), 12.4% (7.4-16.8%) and 27.6% (16.5-39.9%) respectively]. CONCLUSION: CAB-LA has the potential to be substantially more effective than oral PrEP in preventing HIV acquisition in PBW and vertical transmission, and can also modestly reduce HIV incidence at a population level.

Association of naturally acquired type-specific HPV antibodies and subsequent HPV re-detection: systematic review and meta-analysis.

BACKGROUND: Understanding the role of naturally acquired (i.e., infection-induced) human papillomavirus (HPV) antibodies against reinfection is important given the high incidence of this sexually transmitted infection. However, the protective effect of naturally acquired antibodies in terms of the level of protection, duration, and differential effect by sex remains incompletely understood. We conducted a systematic review and a meta-analysis to (1) strengthen the evidence on the association between HPV antibodies acquired through past infection and subsequent type-specific HPV detection, (2) investigate the potential influence of type-specific HPV antibody levels, and (3) assess differential effects by HIV status. METHODS: We searched Embase and Medline databases to identify studies which prospectively assessed the risk of type-specific HPV detection by baseline homologous HPV serostatus among unvaccinated individuals. Random-effect models were used to pool the measures of association of naturally acquired HPV antibodies against subsequent incident detection and persistent HPV positivity. Sources of heterogeneity for each type were assessed through subgroup analyses stratified by sex, anatomical site of infection, male sexual orientation, age group, and length of follow-up period. Evidence of a dose-response relationship of the association between levels of baseline HPV antibodies and type-specific HPV detection was assessed. Finally, we pooled estimates from publications reporting associations between HPV serostatus and type-specific HPV detection by baseline HIV status. RESULTS: We identified 26 publications (16 independent studies, with 62,363 participants) reporting associations between baseline HPV serostatus and incident HPV detection, mainly for HPV-16 and HPV-18, the most detected HPV type. We found evidence of protective effects of baseline HPV seropositivity and subsequent detection of HPV DNA (0.70, 95% CI 0.61-0.80, NE = 11) and persistent HPV positivity (0.65, 95% CI 0.42-1.01, NE = 5) mainly for HPV-16 among females, but not among males, nor for HPV-18. Estimates from 8 studies suggested a negative dose-response relationship between HPV antibody level and subsequent detection among females. Finally, we did not observe any differential effect by baseline HIV status due to the limited number of studies available. CONCLUSION: We did not find evidence that naturally acquired HPV antibodies protect against subsequent HPV positivity in males and provide only modest protection among females for HPV-16. One potential limitation to the interpretation of these findings is potential misclassification biases due to different causes.

Efficacy estimates of oral pre-exposure prophylaxis for HIV prevention in cisgender women with partial adherence.

Pre-exposure prophylaxis (PrEP) with tenofovir (TFV) disoproxil fumarate and emtricitabine administered orally daily is effective in preventing human immunodeficiency virus (HIV) acquisition in both men and women with sufficient adherence; however, the adherence-efficacy relationship in cisgender women has not been well established. We calculated the adherence-efficacy curve for cisgender women by using HIV incidence and plasma TFV concentration data from three trials (FEM-PrEP, VOICE and Partners PrEP). We imputed TFV diphosphate (TFV-DP) concentrations, a measure of long-term adherence, from TFV quantification by using data from the HIV Prevention Trials Network 082 study, which measured both TFV-DP and TFV concentrations. Two, four and seven pills per week reduced HIV incidence by 59.3% (95% credible interval (CrI) 29.9-95.8%), 83.8% (95% CI 51.7-99.8%) and 95.9% (95% CI 72.6-100%), respectively. Our adherence-efficacy curve can be validated and updated by HIV prevention studies that directly measure TFV-DP concentrations. The curve suggests that high adherence confers high protection in cisgender women. However, the lower efficacy with partial adherence highlights the need for new PrEP products and interventions to increase adherence.

The Effect of Disclosure of PrEP Use on Adherence Among African Young Women in an Open-Label PrEP Study: Findings from HPTN 082.

To develop effective PrEP adherence interventions, it is important to understand the interplay between disclosure of pre-exposure prophalxis (PrEP) use, social support, and PrEP adherence. We leveraged the HPTN 082 study conducted among 451 adolescent girls and young women (AGYW) (ages 16 to 25 years, 2016 to 2019) in South Africa and Zimbabwe. Among the 349 who had month three disclosure and PrEP adherence data, 60% (n = 206) felt supported by adults, and 89% (n = 309) disclosed PrEP use to at least one person. PrEP disclosure was not associated with increased adherence, measured by intracellular tenofovir-diphosphate concentrations in dried blood spots. Women who reported having supportive adults, and disclosed to their parents, had higher adherence at 6 months with an increase of 177 fmol/punch (95% CI 12 to 343, t = 2.11, p = 0.04). PrEP interventions that help AGYW identify supportive relationships and effectively communicate the benefits of PrEP may improve PrEP adherence.Clinicaltrials.gov ID number: NCT02732730.

HIV infection.

The AIDS epidemic has been a global public health issue for more than 40 years and has resulted in ~40 million deaths. AIDS is caused by the retrovirus, HIV-1, which is transmitted via body fluids and secretions. After infection, the virus invades host cells by attaching to CD4 receptors and thereafter one of two major chemokine coreceptors, CCR5 or CXCR4, destroying the host cell, most often a T lymphocyte, as it replicates. If unchecked this can lead to an immune-deficient state and demise over a period of ~2-10 years. The discovery and global roll-out of rapid diagnostics and effective antiretroviral therapy led to a large reduction in mortality and morbidity and to an expanding group of individuals requiring lifelong viral suppressive therapy. Viral suppression eliminates sexual transmission of the virus and greatly improves health outcomes. HIV infection, although still stigmatized, is now a chronic and manageable condition. Ultimate epidemic control will require prevention and treatment to be made available, affordable and accessible for all. Furthermore, the focus should be heavily oriented towards long-term well-being, care for multimorbidity and good quality of life. Intense research efforts continue for therapeutic and/or preventive vaccines, novel immunotherapies and a cure.

A decision support tool has similar high PrEP uptake and increases early PrEP persistence in adolescent girls and young women in South Africa: results from a randomized controlled trial.

INTRODUCTION: African adolescent girls and young women (AGYW) have high rates of HIV acquisition and are a priority population for HIV pre-exposure prophylaxis (PrEP). PrEP implementation has been limited by AGYW's low perceived HIV risk and provider demands. A decision support tool (DST) with information about PrEP could improve clients' risk perception, knowledge about PrEP, informed decision-making and motivation to use PrEP based on their risk, facilitating PrEP delivery in primary healthcare (PHC) clinics. METHODS: We designed MyPrEP, a client-facing DST about PrEP and HIV prevention, with youth-friendly information and images. The impact of the MyPrEP tool was assessed among HIV-negative women aged 18-25 years presenting to a PHC clinic in Johannesburg, South Africa from March 2019 to 2020. AGYW were randomized by day to the DST or a general health website as the control condition. A clinician blinded to DST versus control allocation provided standard of care counselling about PrEP, offered PrEP, administered a questionnaire and conducted sexually transmitted infection testing. The primary outcome was PrEP initiation and the secondary outcome was PrEP persistence at 1 month, determined by pharmacy dispensation records. RESULTS: Of 386 AGYW screened, 353 were randomized (DST n = 172, control n = 181) with a median age of 21 years (interquartile range [IQR] 20, 23) and 56% (199/353) attending the clinic for HIV testing, 46% (164/353) using contraception, 15% (53/353) using condoms consistently and 37% (108/353) with a curable sexually transmitted infection. PrEP was initiated by 97% in the DST group and 94% in the control group (OR 1.79; 95% confidence interval, CI = 0.79-1.53), of whom two-thirds planned to continue PrEP until they decided if they liked PrEP. At 1 month, PrEP persistence was 19% in the DST and 10% in the control group (OR 1.97, 95% CI 1.08-3.69). Ninety-nine percent randomized to the DST reported satisfaction with MyPrEP. CONCLUSIONS: Among AGYW attending a South African PHC clinic, PrEP uptake was >90% with two-fold higher PrEP persistence at 1 month in those randomized to use the MyPrEP DST. Given the need for strategies to support PrEP implementation and improve low PrEP persistence among African AGYW, a PrEP DST warrants further evaluation.

The importance of the "how": the case for differentiated service delivery of long-acting and extended delivery regimens for HIV prevention and treatment.

INTRODUCTION: Long-acting and extended delivery (LAED) regimens for HIV treatment and prevention offer unique benefits to expand uptake, effective use and adherence. To date, research has focused on basic and clinical science around the safety and efficacy of these products. This commentary outlines opportunities in HIV prevention and treatment programmes, both for the health system and clients, that could be addressed through the inclusion of LAED regimens and the vital role of differentiated service delivery (DSD) in ensuring efficient and equitable access. DISCUSSION: The realities and challenges within HIV treatment and prevention programmes are different. Globally, more than 28 million people are accessing HIV treatment-the vast majority on a daily fixed-dose combination oral pill that is largely available, affordable and well-tolerated. Many people collect extended refills outside of health facilities with clinical consultations once or twice a year. Conversely, uptake of daily oral pre-exposure prophylaxis (PrEP) has consistently missed global targets due to limited access with high individual cost and lack of choice contributing to substantial unmet PrEP need. Recent trends in demedicalization, simplification, additional method options and DSD for PrEP have led to accelerated uptake as its availability has become more aligned with user preferences. How people currently receive HIV treatment and prevention services and their barriers to adherence must be considered for the introduction of LAED regimens to achieve the expected improvements in access and outcomes. Important considerations include the building blocks of DSD: who (provider), where (location), when (frequency) and what (package of services). Ideally, all LAED regimens will leverage DSD models that emphasize access at the community level and self-management. For treatment, LAED regimens may address challenges with adherence but their delivery should provide clear advantages over existing oral products to be scaled. For prevention, LAED regimens expand a potential PrEP user's choice of methods, but like other methods, need to be delivered in a manner that can facilitate frequent re-initiation. CONCLUSIONS: To ensure that innovative LAED HIV treatment and prevention products reach those who most stand to benefit, service delivery and client considerations during development, trial and early implementation are critical.

Counterfactual estimation of efficacy against placebo for novel PrEP agents using external trial data: example of injectable cabotegravir and oral PrEP in women.

INTRODUCTION: Multiple antiretroviral agents have demonstrated efficacy for human immunodeficiency virus (HIV) pre-exposure prophylaxis (PrEP). As a result, clinical trials of novel agents have transitioned from placebo- to active-controlled designs; however, active-controlled trials do not provide an estimate of efficacy versus no use of PrEP. Counterfactual placebo comparisons using other data sources could be employed to provide this information. METHODS: We compared the active-controlled study (HPTN 084) of injectable cabotegravir (CAB-LA) versus daily oral emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) among women from seven countries in Africa to three external, contemporaneous randomized HIV prevention trials from which we constructed counterfactual placebo estimates. We used direct standardization via analysis weights to achieve the same distribution of person-years between the external study and HPTN 084, across strata predictive of HIV risk (country and selected risk covariates). We estimated prevention efficacy against a counterfactual placebo to provide information on the use of CAB-LA and FTC/TDF compared to no intervention. We compared the counterfactual placebo findings for FTC/TDF to previous placebo-controlled trials, adjusted for observed adherence to daily pills. RESULTS: Distribution of age and baseline prevalence of gonorrhoea and chlamydia were similar among matched counterfactual placebo and observed HPTN 084 arms after standardization. Counterfactual estimates of CAB-LA versus placebo in all three settings showed a consistent risk reduction of 93%-94%, with lower bounds of the confidence intervals above 72%. Observed adherence (quantifiable tenofovir in plasma) in HPTN 084 was 54%-56%, and estimated efficacy of daily oral FTC/TDF against a counterfactual placebo was consistent with a predicted risk reduction of 39%-40% for this level of daily pill use. CONCLUSIONS: Counterfactual placebo rates of HIV acquisition derived from external trial data in similar locations and time can be used to support estimates of placebo-based efficacy of a novel HIV prevention agent. External trial data must be standardized to be representative of the clinical trial cohort testing the novel HIV prevention agent, accounting for confounders.