About

Lawrence C. Long is a Research Associate Professor at the Boston University School of Public Health, with a joint appointment at the University of Witwatersrand in Johannesburg, South Africa. He is a health economist with over 18 years of experience conducting applied research on the economic impact of HIV, tuberculosis, and related conditions within South Africa and the region. Lawrence has extensive experience in organizational management, leadership, and grant management, having led a South African research group as deputy director. His training includes economics, finance, mathematics, research methodology, and behavioral science. He is the principal investigator of multiple research projects, including an NIH K01 award focused on using behavioral economics to improve the uptake and persistence of pre-exposure prophylaxis for HIV prevention among men who have sex with men, and he is involved in a Gates-funded program to build behavioral economics capacity for HIV in South Africa. Lawrence has published widely in peer-reviewed journals and has contributed to research on HIV, TB, and health service delivery, emphasizing applied economic analysis and behavioral science approaches.

Research topics

• Family medicine
• Medicine
• Medical physics
• Pediatrics
• Physical therapy
• Surgery
• Internal medicine
• Psychology

Selected publications

• Data from: Implementation of Option B and a fixed-dose combination antiretroviral regimen for prevention of mother-to-child transmission of HIV in South Africa: a model of uptake and adherence to care

  University of Witwatersrand · 2026-03-02

  datasetOpen access

  IntroductionInitiating and retaining pregnant women on antiretroviral therapy (ART) to prevent mother-to-child HIV transmission (PMTCT) remains a major challenge facing African HIV programs, particularly during the critical final months prior to delivery. In 2013, South Africa implemented its “Option B” PMTCT regimen (three-drug ART throughout pregnancy and breastfeeding, regardless of maternal CD4 count) and introduced once-daily fixed-dose combinations and lifelong ART. Currently, the uptake of Option B and its possible impact on adherence to PMTCT during the critical final months of pregnancy is unclear.Materials and Methods We prospectively collected visit data from a cohort of adult, HIV-infected, pregnant women between July 2013-August 2014 to estimate three models of adherence to PMTCT during the final 16 weeks immediately preceding delivery. Adherence was defined according to possession of antiretroviral drugs, which was inferred from clinic visit records under varying assumptions in each model. We describe uptake of the PMTCT regimen, gestational age at initiation, and model possible scenarios of adherence through delivery after the implementation of Option B.ResultsAmong 138 women enrolled (median (IQR) age 28 years (24-32), median CD4 count 378 cells/mm3), median (IQR) gestational age at initiation was 22 weeks (16-26). Estimates of adherence during the final 16 weeks of pregnancy prior to delivery ranged from 75% (52-89%) under the best-case scenario assumptions to 52% (30-75%) under the worst-case scenario assumptions. Estimates of the proportion of women who would achieve 80% adherence to PMTCT were <50% across all models. ConclusionsDespite the switch to Option B and once-daily dosing, South African women continue to initiate PMTCT late in pregnancy, and estimations of regimen adherence, as modelled using PMTCT visit attendance data, is poor, with <50% of women reaching 80% adherence during final months of pregnancy across all models. Further guideline changes and interventions are needed to achieve vertical transmission goals.

  PublisherDOI

• <i>“Taking PrEP every day for me is a challenge”:</i> Barriers, and facilitators to accessing HIV pre-exposure prophylaxis (PrEP) services among young people in Gauteng, South Africa

  medRxiv · 2026-01-16

  articleOpen access

  Background: Pre-exposure prophylaxis (PrEP) is an effective HIV prevention strategy, yet uptake remains suboptimal and ensuring access to PrEP services among young people is critical. We explored the barriers and facilitators associated with accessing PrEP among young people. Methods: Focus group discussions (FGDs) were conducted in April and May 2023 in the City of Johannesburg district in South Africa. Participants were adult males and females (ages 18-35) self-reporting as HIV negative with or without previous PrEP use and exposure. We analysed transcripts using a deductive and inductive thematic approach. Two transcripts were coded by three coders to test reliability and saturation was reached when no new themes emerged. Results: Findings were mapped to the Socio-Ecological Model (SEM). Key barriers emerged across levels. Individual level barriers included difficulty adhering to daily oral PrEP and fear of needles. Interpersonal challenges included anxiety about disclosing PrEP use to partners or family. Institutional and organisational barriers involved long clinic queues, negative staff attitudes, limited confidentiality and inadequate PrEP information. At the community level, stigma and misconceptions linking PrEP to HIV treatment deterred uptake. Several facilitators emerged. Individual motivation to remain HIV negative was a strong driver of uptake. Supportive relationships and open communication with friends and family enhanced acceptance. Organisational enablers included access to clear information, youth-friendly services, competent providers and delivery options such as home delivery or pharmacy access. Community awareness initiatives reduced stigma and structural support in a form of free PrEP improved affordability and access. Conclusion: Young people's access to PrEP is shaped by interactions across individual, relational, institutional, community, and structural levels. Tailored interventions that address personal barriers, strengthen supportive environments, improve service delivery, and ensure affordability are likely to strengthen uptake and adherence. These findings highlight the need for multilevel strategies to optimize PrEP implementation among youth.

  PublisherOA PDFDOI

• Data from: Implementation of Option B and a fixed-dose combination antiretroviral regimen for prevention of mother-to-child transmission of HIV in South Africa: a model of uptake and adherence to care

  Figshare · 2026-03-02

  dataset

  IntroductionInitiating and retaining pregnant women on antiretroviral therapy (ART) to prevent mother-to-child HIV transmission (PMTCT) remains a major challenge facing African HIV programs, particularly during the critical final months prior to delivery. In 2013, South Africa implemented its “Option B” PMTCT regimen (three-drug ART throughout pregnancy and breastfeeding, regardless of maternal CD4 count) and introduced once-daily fixed-dose combinations and lifelong ART. Currently, the uptake of Option B and its possible impact on adherence to PMTCT during the critical final months of pregnancy is unclear.Materials and Methods We prospectively collected visit data from a cohort of adult, HIV-infected, pregnant women between July 2013-August 2014 to estimate three models of adherence to PMTCT during the final 16 weeks immediately preceding delivery. Adherence was defined according to possession of antiretroviral drugs, which was inferred from clinic visit records under varying assumptions in each model. We describe uptake of the PMTCT regimen, gestational age at initiation, and model possible scenarios of adherence through delivery after the implementation of Option B.ResultsAmong 138 women enrolled (median (IQR) age 28 years (24-32), median CD4 count 378 cells/mm3), median (IQR) gestational age at initiation was 22 weeks (16-26). Estimates of adherence during the final 16 weeks of pregnancy prior to delivery ranged from 75% (52-89%) under the best-case scenario assumptions to 52% (30-75%) under the worst-case scenario assumptions. Estimates of the proportion of women who would achieve 80% adherence to PMTCT were &lt;50% across all models. ConclusionsDespite the switch to Option B and once-daily dosing, South African women continue to initiate PMTCT late in pregnancy, and estimations of regimen adherence, as modelled using PMTCT visit attendance data, is poor, with &lt;50% of women reaching 80% adherence during final months of pregnancy across all models. Further guideline changes and interventions are needed to achieve vertical transmission goals.

  DOI

• Evaluating the acceptability, usability and clinical appropriateness of <i>Your Path</i> , an AI-powered tool facilitating relevant access to HIV services post-HIV self-testing in South Africa

  medRxiv · 2025-11-13

  preprintOpen access

  ABSTRACT Timely linkage to HIV prevention and treatment services following HIV self-testing (HIVST) remains a challenge in many countries. While HIVST offers privacy and convenience for individuals to know their HIV status, many do not engage in follow-up care due to behavioural barriers like uncertainty about next steps, stigma, and privacy concerns. This study evaluated the acceptability, usability, and clinical appropriateness of Your Path , an Artificial Intelligence (AI)-powered tool designed to facilitate linkage to appropriate HIV services following HIVST. This study was conducted with community members (CMs) and healthcare providers (HCPs), recruited from a research site in an urban area in South Africa. CMs were randomly assigned a mock HIV test result and completed a pre-test survey assessing intentions to seek HIV services, followed by a simulated HIVST session guided by Your Path . A post-test survey then evaluated changes in intention to seek care (a proxy for uptake of care) and a System Usability Scale (SUS) measured usability of the tool. A sub-sample of 25 CMs completed in-depth interviews exploring their experience with Your Path . HCPs reviewed transcripts of CM tool interactions to assess clinical appropriateness, completeness and relevance of the generated summaries. Qualitative data were analysed thematically, and results aligned with the Theoretical Framework of Acceptability (TFA). Of the 100 enrolled CMs, 59.0% were female and 51.0% received a mock HIV-negative result. After interacting with Your Path , 91.0% of CMs reported that it positively influenced their intention to access HIV services. The tool demonstrated high usability, with a mean SUS score of 81.6 (SD 17.5). Most found Your Path easy to use (83.7%) and did not need assistance (76.4%), and 94.9% expressed willingness to use it again. However, 15.3% noted that it did not always provide consistent responses to questions and that responses varied or were unclear. CMs described Your Path as a helpful guide with a user-friendly design. Most appreciated its private, non-judgmental tone, which helped reduce stigma during interactions. Some valued the sense of confidentiality offered by the tool, while others expressed concerns about the protection of their information. HCPs found the conversational summaries clinically appropriate, and cited the tool as informative and beneficial for supporting linkage to HIV care. Limitations in emotional responsiveness and potential language barriers were noted. Recommendations included integrating local languages, offering data-free access, and aligning with existing healthcare systems to improve reach and coordination of care. Your Path was acceptable, usable, and clinically appropriate for supporting linkage to HIV services after HIVST, and showed potential to support intentions to seek HIV care. Larger in-field studies are needed to understand the implementation, cost and sustainability of digital interventions in public health.

  PublisherOA PDFDOI

• Client preferences for service delivery during the early treatment period in South Africa and Zambia: Mixed-method findings from a discrete choice experiment and concurrent focus group discussions

  medRxiv · 2025-07-29

  preprintOpen access

  Background: Disengagement from antiretroviral therapy (ART) is common in the first 6 months of HIV treatment in sub-Saharan Africa. Using mixed-methods we aimed to understand preferences during this early treatment period. Methods: Between 8/2023-11/2023, adults who had initiated/re-initiated ART a median of 8 months prior were enrolled at 18 healthcare facilities across South Africa (SA) and Zambia to participate in a discrete choice experiment (DCE) and focus group discussion (FGD). In the DCE, participants made 9 choices between unique service delivery scenarios (each comprised of 8 attributes). Analyzed using a conditional logit model, we report findings using odds ratios (95% confidence intervals). Following the DCE, FGDs explored barriers to care seeking and care preferences. Thematic analysis was used to interpret FGDs. DCE and FGD findings were triangulated to understand preferences. Results: We enrolled 250 respondents: 128 in Zambia (55% female, median age 35); 122 in SA (83% female, median age 33). Community-based services were less favorable to respondents than clinic-based care (SA: 0.62 (95% CI 0.52, 0.75); Zambia: 0.44 (0.36, 0.53)). Respondents preferred 6-month dispensing (SA: 1.3 (1.1, 1.6); Zambia: 2.1 (1.8, 2.6)) to 1-month intervals. Respondents also preferred accessing services from friendly providers. Qualitative insights corroborated DCE findings. They also revealed frustrations with long wait times at clinics. Conclusion: Utilizing a decision experiment with qualitative methods allowed us to uniquely capture drivers of client decision-making and the nuanced factors that shape experiences. Results suggest that enrollment in lower-intensity models may improve client experiences during the early treatment period.

  PublisherOA PDFDOI

• Managing the move: HIV and coping for men moving to Johannesburg

  AIDS Care · 2025-11-19

  article

  = 0.022) scores were higher among men with citizenship/permanent versus those without. Targeted coping support for men without permanent residency status may improve engagement in HIV care. Although our findings are not generalizable to all migrant population, further research may help to understand how religious beliefs impact coping and clinical outcomes among South African men living with HIV to inform interventions.

  PublisherDOI

• Using sputum and tongue swab specimens for in-home point-of-care targeted universal testing for tuberculosis of household contacts: an acceptability and feasibility analysis

  BMJ Global Health · 2025-08-01 · 8 citations

  articleOpen access

  INTRODUCTION: Effective strategies are essential for early tuberculosis (TB) detection. Reliance on passive case detection, symptom screening and collection of sputum results in delayed or undiagnosed TB, contributing to on-going TB transmission. This study assessed the acceptability of in-home targeted universal TB testing (TUTT) using GeneXpert MTB/RIF Ultra at point-of-care (POC) during household contact investigations (HCIs) and the feasibility of using sputum and tongue swab specimens. METHODS: The TB Home Study sought to evaluate the predictive value of different specimen types for use as a household-level triage test for TB. Household contacts of people with TB residing in the Buffalo City Metro Health District (Eastern Cape Province, South Africa) who received in-home POC TUTT through the TB Home Study were asked to complete a post-test acceptability survey. The survey assessed the level of comfort, confidence in the test results and perceived appropriateness of in-home POC TUTT. A feasibility framework was used to assess the feasibility of using sputum and tongue swab specimens for testing. RESULTS: Of the 325 eligible household contacts, 281/325 (86.5%) provided consent. Of those contacts, 278/281 (98.9%) provided a tongue swab, and 50/281 (17.8%) could expectorate sputum. All specimens were successfully prepared for immediate in-home testing. Of the 172 tongue swab-based tests performed, 169 (98.3%) produced a valid result, whereas 47 of 49 (95.9%) sputum-based tests had a valid result. An immediate tongue swab-based test result was available for 274/278 (98.6%) clients compared with 47/49 (95.9%) sputum-based test results. The mean in-home POC TUTT acceptability score (5=highly acceptable) was 4.2/5 (SD=0.4). CONCLUSION: In-homePOC TUTT using sputum and tongue swab specimens was highly acceptable and feasible. Tongue swabs greatly increased the testing rates owing to the high sample collection yield. Combining sputum and tongue swabs for in-home POC testing offers a promising strategy to improve TB case detection and reduce diagnostic delays.

  PublisherOA PDFDOI

• Designing Artificial Intelligence-Powered Health Care Assistants to Reach Vulnerable Populations: A Discrete Choice Experiment Among South African University Students

  Mayo Clinic Proceedings Digital Health · 2025-07-15

  articleOpen access

  Objective: To understand what preferences are important to university students in South Africa when engaging with a hypothetical artificial intelligence-powered health care assistant (AIPHA) to access health information using a discrete choice experiment. Patients and Methods: We conducted an unlabeled, forced choice discrete choice experiment among adult South African university students through Prolific, an online research platform, from June 26, 2024 to August 31, 2024. Each choice option described a hypothetical AIPHA using 8 attribute characteristics (cost, confidentiality, security, health care topics, language, persona, access, and services). Participants were presented with 10 choice sets each comprised of 2 choice options and asked to choose between the 2. A conditional logit model was used. Results: Three hundred participants were recruited and enrolled. Most participants were Black, born in South Africa, heterosexual, working for a wage, and had a mean age of 26.5 years (SD, 6.0). Language, security, and receiving personally tailored advice were the most important attributes for AIPHA. Participants strongly preferred the ability to communicate with the AIPHA in any South African language of their choosing instead of only English and receive information about health topics specific to their context including information on clinics geographically near them. The results were consistent when stratified by sex and socioeconomic status. Conclusion: Participants had strong preferences for security and language, which is in line with previous studies where successful uptake and implementation of such health interventions clearly addressed these concerns. These results build the evidence base for how we might engage young adults in health care through technology effectively.

  PublisherOA PDFDOI

• Effectiveness of the Common Elements Treatment Approach (CETA) for mental and behavioral health outcomes among women struggling to remain adherent to HIV treatment and who have experienced intimate partner violence in South Africa: A randomised controlled trial

  medRxiv · 2025-10-15

  preprintOpen access

  ABSTRACT Background Rates of intimate partner violence (IPV) and HIV in South Africa are among the highest globally. IPV is associated with a range of adverse mental health and HIV outcomes. The Common Elements Treatment Approach (CETA) is a transdiagnostic, evidence-based intervention delivered by lay providers. Objective To compare the effectiveness of CETA to active attention control in reducing IPV, depression, Post-Traumatic Stress Disorder (PTSD), and substance use among women at risk of poor HIV outcomes who have experienced IPV. Methods Women living with HIV with an unsuppressed viral load or at risk for poor adherence and experienced past 12-month IPV were recruited from Johannesburg-area clinics and randomised 1:1 to CETA or control (SMS HIV appointment reminders plus safety checks and planning). The primary trial outcome was HIV retention and viral suppression, reported elsewhere. This paper reports secondary outcomes, evaluated at three and 12 months: IPV, depression, PTSD, and substance use. Findings Participants were enrolled between November 11, 2021 to July 19, 2023 and randomised to CETA (N=202) or control (N=197). In the intent to treat analysis, the Cohen’s d treatment effect for depression at three months was 0.24 (difference in mean change -3.1; 95% CI: -6.1, 0.1) and 0.48 at 12 months (-6.2; 95% CI: -9.5, -2.8). The PTSD treatment effect was 0.39 at three (-0.3; 95% CI: -0.5, -0.1) and 0.47 at 12 months (-0.3; 95% CI: -0.5, -0.2). Effect sizes were larger in a subgroup of participants with the top 50% of baseline symptom scores (depression: d=0.50, d=0.74; PTSD: d=0.58, d=0.94, at three and 12 months, respectively). There were no statistically significant differences in change for substance use or IPV. At baseline, only 12% of participants had past 3-month substance use and 32% had past 3-month or ongoing experiences of IPV, which made these outcomes challenging to evaluate. Conclusions CETA was effective for reducing depression and PTSD including among high severity participants and at an extended follow-up. Future studies with increased power for substance use and IPV outcomes are warranted. Clinical implications CETA is a recommended treatment for depression and PTSD among this population. Trial registration number Clinicaltrials.gov NCT04242992 , registered January 27, 2020 Key Messages What is already known about this topic? Intimate partner violence (IPV) and related mental health problems are common in South Africa and can lead to poor HIV outcomes, such as low retention in care and viral non-suppression. There is a lack of evidence-based mental healthcare options for women living with HIV who have experienced IPV. What this study adds Among women living with HIV and past-year IPV experiences, we found that Common Elements Treatment Approach (CETA) was an effective treatment for depression and PTSD compared to a control condition. How this study might affect research, practice, or policy CETA is recommended to treat common mental health problems among women with HIV and experiences of IPV.

  PublisherOA PDFDOI

• HIV Care for Men on the Move: A Qualitative Study to Inform Status-Neutral HIV Service Delivery for Mobile Men in Johannesburg, South Africa

  AIDS and Behavior · 2025-03-03

  article
  PublisherDOI

Recent grants

• Using behavioral economics to improve the uptake of and persistence on pre-exposure prophylaxis in men who have sex with men to prevent HIV infection

  NIH · $173k · 2020–2025

• Using behavioral economics to improve the uptake of and persistence on pre-exposure prophylaxis in men who have sex with men to prevent HIV infection

  NIH · $692k · 2020–2026

Frequent coauthors

• Sydney Rosen

  Boston University

  208 shared

• Matthew P. Fox

  University of the Witwatersrand

  194 shared

• Ian Sanne

  Advanced Biological Laboratories (Luxembourg)

  128 shared

• Brooke E. Nichols

  Foundation for Innovative New Diagnostics

  105 shared

• Alana T. Brennan

  Africa Health Research Institute

  95 shared

• Denise Evans

  Office Of Health Economics

  65 shared

• Gesine Meyer‐Rath

  Boston University

  58 shared

• Mhairi Maskew

  University of the Witwatersrand

  47 shared

Education

• Doctorate of Philosophy

  University of the Witwatersrand

• Masters of Commerce, School of Economics and Business Science

  University of the Witwatersrand

• Bachelors of Business Science - Economics

  University of Cape Town

• Master of Science Behavioural Science, Psychology and Behavioural Science

  London School of Economics and Political Science

  2023

Awards & honors

• NIH K01 award