Yesim Tozan
Yesim Tozan
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Associate Professor of Global and Environmental Health
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Professional overview
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Dr. Yesim Tozan’s research centers on health decision science and priority setting, and explores the costs and cost-effectiveness of health care interventions using decision analytic models and the issues of health care resource allocation in low- and middle-income countries. Her main focus has been infectious disease prevention and control with an emphasis on dengue and malaria. Dr. Tozan is currently leading a health economics work package in a European Union-funded research project on dengue surveillance and control with field sites in Sri Lanka and Thailand. She is also leading a prospective multi-center study on the cost of dengue illness in international travelers utilizing a network of travel clinics in Europe, the US, the Middle East and Australia. Most recently, she has been working on economic evaluation of artemisinin-based combination therapies for the treatment of uncomplicated childhood malaria using data from multi-site randomized clinical trials in Africa and Asia. Dr. Tozan was a task force associate for the UN Millennium Project’s Task Force on HIV/AIDS, Malaria, Tuberculosis and Access to Essential Medicines and was lead author of the malaria task force report entitled “Coming to grips with malaria in the new millennium.”
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Education
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BS, Environmental Engineering, Istanbul Technical University, TurkeyMS, Environmental Technology, Bogazici University, TurkeyMA, Public Affairs, Princeton University, Princeton, NJPhD, Public Affairs, Princeton University, Princeton, NJ
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Areas of research and study
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Cost EffectivenessCost-effective Health Programs and PoliciesEconomic EvaluationHealth EconomicsInfectious DiseasesPrevention Interventions
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Publications
Publications
Countries’ progress towards Global Health Security (GHS) increased health systems resilience during the Coronavirus Disease-19 (COVID-19) pandemic: A difference-indifference study of 191 countries
AbstractHeadley, T. Y., Kim, S., & Tozan, Y. (n.d.).Publication year
2025Journal title
PLOS Global Public HealthVolume
5Issue
1AbstractResearch on health systems resilience during the Coronavirus Disease-2019 pandemic frequently used the Global Health Security Index (GHSI), a composite index scoring countries’ health security and related capabilities. Conflicting results raised questions regarding the validity of the GHSI as a reliable index. This study attempted to better characterize when and to what extent countries’ progress towards Global Health Security (GHS) augments health systems resilience. We used longitudinal data from 191 countries and a difference-in-difference (DiD) causal inference strategy to quantify the effect of countries’ GHS capacity as measured by the GHSI on their coverage rates for essential childhood immunizations, a previously established proxy for health systems resilience. Using a sliding scale of cutoff values with step increments of one, we divided countries into treatment and control groups and determined the lowest GHSI score at which a safeguarding effect was observed. All analyses were adjusted for potential confounders. World Bank governance indicators were employed for robustness tests. While countries with overall GHSI scores of 57 and above prevented declines in childhood immunization coverage rates from 2020–2022 (coef: 0.91; 95% CI: 0.41–1.41), this safeguarding effect was strongest in 2021 (coef: 1.23; 95% CI: 0.05–2.41). Coefficient sizes for overall GHSI scores were smaller compared to several GHSI sub-components, including countries’ environmental risks (coef: 4.28; 95% CI: 2.56–5.99) and emergency preparedness and response planning (coef: 1.82; 95% CI: 0.54–3.11). Our findings indicate that GHS was positively associated with health systems resilience during the pandemic (2020) and the following two years (2021–2022), that GHS may have had the most significant protective effects in 2021 as compared with 2020 and 2022, and that countries’ underlying characteristics, including governance quality, bolstered health systems resilience during the pandemic.Cultural adaptation of clinic-based pediatric hiv status disclosure intervention with task shifting in Eastern Uganda
AbstractKirabira, J., Nakigudde, J., Huang, K. Y., Ashaba, S., Nambuya, H., Tozan, Y., & Yang, L. H. (n.d.).Publication year
2025Journal title
AIDS Research and TherapyVolume
22Issue
1AbstractBackground: HIV status disclosure remains a major challenge among children living with perinatally acquired HIV with many taking treatment up to adolescence without knowing their serostatus. This non-disclosure is influenced by factors like fear of the negative consequences of disclosure. Since HIV status disclosure has been found to have good effects including improving treatment adherence and better mental health outcomes, there is a need to design interventions aimed at improving disclosure rates among children living with HIV. This study aims at adapting a clinic-based pediatric HIV status disclosure intervention and tasking shifting from healthcare workers to caregiver peer supporters in Eastern Uganda. Methods: The adaptation process involved consultations with caregivers, healthcare workers involved in the care of children living with HIV, researchers in this field, intervention developers, and other experts and stakeholders. This was done through conducting FGDs with HCWs, caregivers, and peer supporters and consultations with researchers in the field of HIV. The original intervention manual was translated to Lusoga which is the commonly spoken dialect in this region. Collected qualitative data were analyzed using an inductive approach to develop themes and subthemes. Written informed consent will be obtained from all participants before participation in the study. Results: A total of 28 participants were involved in the FGDs, while two pediatricians and two HIV researchers/specialists were consulted. Six themes were generated in relation to all suggested changes to the original manual which were related to: (1) sociocultural beliefs/norms/perceptions (5 FGDs), (2) boosting caregiver’s confidence for disclosure (5FGDs), (3) disclosure mode, environment, and person (4 FGDs), (4) health facility/system related changes (3 FGDs), (5) reorganization/paraphrasing (3FGDs) and (6) age appropriateness (2FGDs). Conclusion: This study emphasized that whereas some aspects of intervention can apply to various contexts, there is a need for cross-cultural adaptation of interventions before being implemented in settings where they were not developed.Social and Psychological Mediators of Sexual and Physical Male-Perpetrated Intimate Partner Violence Against Young African American Women: The Role of Alcohol Use and Drinking Context
AbstractCapasso, A., Pahl, K., Tozan, Y., & DiClemente, R. J. (n.d.).Publication year
2025Journal title
Journal of Interpersonal ViolenceAbstractProblem alcohol use is prevalent among women who experience male-perpetrated intimate partner violence (IPV). However, the pathways by which this occurs remain poorly understood and understudied among African American women. This study sought to examine context-specific social and psychological mediators of this association. Using structural equation modeling (SEM), we tested a conceptual framework predicting problem alcohol use within 3 months of experiencing physical and/or sexual IPV. The sample included 508 young African American women (median age 21, interquartile range 19–22 years). A modified SEM met prespecified global and local fit index criteria. The model identified four indirect paths from IPV to problem alcohol use. Three of the paths were through the endorsement of drinking contexts: negative coping, social drinking, and intimate drinking. Negative coping and social drinking emerged as the most salient pathways (β =.431, 95% CI [0.107, 0.754]; β =.472 [0.103, 0.841], respectively). A fourth path operated via depressive symptomatology and negative coping. The model predictors explained 35% of the variance in problem alcohol use; findings were consistent with full mediation of IPV and problem drinking. These findings increase the understanding of problem alcohol use among African American women who experience IPV and identify modifiable context-specific risk factors for problem alcohol use. Interventions to reduce problem drinking could incorporate trauma-informed counseling, as part of integrated IPV and substance use care, to reduce depressive symptomatology and enhance drinking refusal skills in response to situational drinking.Spatio-temporal modelling and prediction of malaria incidence in Mozambique using climatic indicators from 2001 to 2018
AbstractArmando, C. J., Rocklöv, J., Sidat, M., Tozan, Y., Mavume, A. F., & Sewe, M. O. (n.d.).Publication year
2025Journal title
Scientific reportsVolume
15Issue
1AbstractAccurate malaria predictions are essential for implementing timely interventions, particularly in Mozambique, where climate factors strongly influence transmission. This study aims to develop and evaluate a spatial–temporal prediction model for malaria incidence in Mozambique for potential use in a malaria early warning system (MEWS). We used monthly data on malaria cases from 2001 to 2018 in Mozambique, the model incorporated lagged climate variables selected through Deviance Information Criterion (DIC), including mean temperature and precipitation (1–2 months), relative humidity (5–6 months), and Normalized Different Vegetation Index (NDVI) (3–4 months). Predictive distributions from monthly cross-validations were employed to calculate threshold exceedance probabilities, with district-specific thresholds set at the 75th percentile of historical monthly malaria incidence. The model’s ability to predict high and low malaria seasons was evaluated using receiver operating characteristic (ROC) analysis. Results indicated that malaria incidence in Mozambique peaks from November to April, offering a predictive lead time of up to 4 months. The model demonstrated high predictive power with an area under the curve (AUC) of 0.897 (0.893–0.901), sensitivity of 0.835 (0.827–0.843), and specificity of 0.793 (0.787–0.798), underscoring its suitability for integration into a MEWS. Thus, incorporating climate information within a multisectoral approach is essential for enhancing malaria prevention interventions effectiveness.Trajectories of Physical Violence Against Latinas and Black Women: The Protective Role of Parents, Neighborhoods, and Schools
AbstractCapasso, A., Tozan, Y., DiClemente, R. J., & Pahl, K. (n.d.).Publication year
2025Journal title
Violence Against WomenAbstractUnderstanding the heterogeneous experiences of violence experienced by Black and Latina women over the life course is critical to prevention. We identified four physical violence trajectories experienced by 361 Black and Latina women followed from ages 14 to 39: low/none (44.0%), persistent-moderate (36.8%), peak in the 20s (11.9%), and persistent-high (7.2%) violence exposure. Childhood abuse predicted membership in the three violence-exposed groups, whereas parental closeness, school academic orientation, and neighborhood safety were protective factors. Public health interventions aimed at preventing childhood trauma and ensuring safe interpersonal relationships and environments for girls to thrive are urgently needed.A pre-post evaluation study of a social media-based COVID-19 communication campaign to improve attitudes and behaviors toward COVID-19 vaccination in Tanzania
AbstractKim, S., Lilani, A., Redemptus, C., Campana, K., & Tozan, Y. (n.d.).Publication year
2024Journal title
PloS oneVolume
19Issue
5AbstractIn Tanzania, the One by One: Target COVID-19 campaign was launched nationally in July 2022 to address the prevalent vaccine hesitancy and lack of confidence in COVID-19 vaccines. The campaign mobilized social media influencers and viral content with the ultimate goal of increasing COVID-19 vaccine uptake in the country. The objective of this study was to empirically assess the impact of the campaign on three outcomes: vaccine confidence, vaccine hesitancy, and vaccination status. Using programmatic data collected through an online survey before and after the campaign, we conducted a difference-in-difference (DiD) analysis and performed a crude, adjusted, and propensity score-matched analysis for each study outcome. Lastly, to observe whether there was any differential impact of the campaign across age groups, we repeated the analyses on age-stratified subgroups. Data included 5,804 survey responses, with 3,442 and 2,362 responses collected before and after the campaign, respectively. Although there was only weak evidence of increased COVID-19 vaccine confidence in the campaign-exposed group compared to the control group across all age groups, we observed a differential impact among different age groups. While no significant change was observed among young adults aged 18–24 years, the campaign exposure led to a statistically significant increase in vaccine confidence (weighted/adjusted DiD coefficient = 0.76; 95% CI: 0.06, 1.5; p-value = 0.034) and vaccination uptake (weighted/adjusted DiD coefficient = 1.69.; 95% CI: 1.02, 2.81; p-value = 0.023) among young adults aged 25–34 years. Among adults aged 35 years and above, the campaign exposure led to a significant decrease in vaccine hesitancy (weighted/adjusted DiD coefficient = -15; 95% CI: -21, -8.3; p-value<0.001). The social media campaign successfully improved vaccine hesitancy, confidence, and uptake in the Tanzanian population, albeit to varying degrees across age groups. Our study provides valuable insights for the planning and evaluation of similar social media communication campaigns aiming to bolster vaccination efforts.Childhood Violence, High School Academic Environment, and Adult Alcohol Use Among Latinas and Black Women: A Structural Equation Modeling Study
AbstractCapasso, A., Tozan, Y., DiClemente, R. J., & Pahl, K. (n.d.).Publication year
2024Journal title
Journal of Interpersonal ViolenceVolume
39Issue
23Page(s)
4924-4953AbstractObjective: Young Latinas and Black women drink less than women of other racial/ethnic groups but experience more alcohol-related problems in midlife. This study aims to identify modifiable factors to prevent adult onset of alcohol use disorder (AUD) in this population. Methods: Data were collected at six time points as part of the Harlem Longitudinal Development Study from 365 Latinas (47%) and Black (53%) women (mean age at time 1 = 14, standard deviation 1.3). Structural equation modeling was used to test hypothesized pathways from childhood physical and sexual abuse to AUD via depressive mood, anxiety disorders, and somatic complaints in the 20s. We also tested the moderation effect of the high school academic environment by including in the structural equation model two latent variable interaction terms between the school environment and each of the abuse variables. Results: Childhood physical and sexual abuse was positively associated with depressive mood, anxiety disorders, and somatic complaints when participants were in the 20s. Depressive mood mediated childhood abuse and AUD when women were in the 30s. The high school academic environment attenuated the effect of physical, but not sexual abuse, on depressive mood (β = −0.59, B = −9.38, 95% CI [−14.00, −4.76]), anxiety symptoms (β = −0.61, B = −14.19, 95% CI [−21.76, −6.61]), appetite loss (β = −0.41, B = −10.52, 95% CI [−15.61, −5.42]), and sleeplessness (β = −0.50, B = −9.56, 95% CI [−13.95, −5.17]) in the early 20s. Conclusions: Our findings underscore the need to invest in early violence prevention interventions and in education to ensure equitable access to quality, academically oriented, and safe schools.Costing of a Combination Intervention (Kyaterekera) Addressing Sexual Risk-Taking Behaviors among Vulnerable Women in Southern Uganda
AbstractTozan, Y., Kiyingi, J., Kim, S., Nabayinda, J., Namuwonge, F., Nsubuga, E., Nakabuye, F., Sensoy, O. B., Nabunya, P., Mayo-Wilson, L. J., McKay, M. M., Witte, S. S., & Ssewamala, F. M. (n.d.).Publication year
2024Journal title
American Journal of Tropical Medicine and HygieneVolume
110Issue
5Page(s)
1046-1056AbstractIn Uganda, women engaged in sex work (WESW) are a marginalized population at the intersection of multiple vulnerabilities. The Kyaterekera intervention is targeted at WESW in Rakai and the greater Masaka regions in Uganda and combines a traditional HIV risk-reduction approach with a savings-led economic empowerment intervention and financial literacy training. We estimated the economic costs of the Kyaterekera intervention from a program provider perspective using a prospective activity-based micro-costing method. All program activities and resource uses were measured and valued across the control arm receiving a traditional HIV risk-reduction intervention and the treatment arm receiving a matched individual development savings account and financial literacy training on top of HIV risk reduction. The total per-participant cost by arm was adjusted for inflation and discounted at an annual rate of 3% and presented in 2019 US dollars. The total per-participant costs of the control and intervention arms were estimated at $323 and $1,435, respectively, using the per-protocol sample. When calculated based on the intent-to-treat sample, the per-participant costs were reduced to $183 and $588, respectively. The key cost drivers were the capital invested in individual development accounts and personnel and transportation costs for program operations, linked to WESW's higher mobility and the dispersed pattern of hot spot locations. The findings provide evidence of the economic costs of implementing a targeted intervention for this marginalized population in resource-constrained settings and shed light on the scale of potential investment needed to better achieve the health equity goal of HIV prevention strategies.Spatial-temporal analysis of climate and socioeconomic conditions on cholera incidence in Mozambique from 2000 to 2018: an ecological longitudinal retrospective study
AbstractArmando, C. J., Rocklöv, J., Sidat, M., Tozan, Y., Mavume, A. F., Bunker, A., & Sewe, M. O. (n.d.).Publication year
2024Journal title
BMJ openVolume
14Issue
8AbstractObjectives This study aims to assess both socioeconomic and climatic factors of cholera morbidity in Mozambique considering both spatial and temporal dimensions. Design An ecological longitudinal retrospective study using monthly provincial cholera cases from Mozambican Ministry of Health between 2000 and 2018. The cholera cases were linked to socioeconomic data from Mozambique Demographic and Health Surveys conducted in the period 2000-2018 and climatic data; relative humidity (RH), mean temperature, precipitation and Normalised Difference Vegetation Index (NDVI). A negative binomial regression model in a Bayesian framework was used to model cholera incidence while adjusting for the spatiotemporal covariance, lagged effect of environmental factors and the socioeconomic indicators. Setting Eleven provinces in Mozambique. Results Over the 19-year period, a total of 153 941 cholera cases were notified to the surveillance system in Mozambique. Risk of cholera increased with higher monthly mean temperatures above 24°C in comparison to the reference mean temperature of 23°C. At mean temperature of 19°C, cholera risk was higher at a lag of 5-6 months. At a shorter lag of 1 month, precipitation of 223.3 mm resulted in an 57% increase in cholera risk (relative risk, RR 1.57 (95% CI 1.06 to 2.31)). Cholera risk was greatest at 3 lag months with monthly NDVI of 0.137 (RR 1.220 (95% CI 1.042 to 1.430)), compared with the reference value of 0.2. At an RH of 54%, cholera RR was increased by 62% (RR 1.620 (95% CI 1.124 to 2.342)) at a lag of 4 months. We found that ownership of radio RR 0.29, (95% CI 0.109 to 0.776) and mobile phones RR 0.262 (95% CI 0.097 to 0.711) were significantly associated with low cholera risk. Conclusion The derived lagged patterns can provide appropriate lead times in a climate-driven cholera early warning system that could contribute to the prevention and management of outbreaks.The synergistic impact of Universal Health Coverage and Global Health Security on health service delivery during the Coronavirus Disease-19 pandemic: A difference-indifference study of childhood immunization coverage from 192 countries
AbstractKim, S., Headley, T. Y., & Tozan, Y. (n.d.).Publication year
2024Journal title
PLOS Global Public HealthVolume
4Issue
5AbstractUniversal Health Coverage (UHC) and Global Health Security (GHS) are two high-priority global health agendas that seek to foster health system resilience against health emergencies. Many countries have had to prioritize one agenda over the other due to scarce resources and political pressures. To aid policymakers’ decision-making, this study investigated the individual and synergistic effects of countries’ UHC and GHS capacities in safeguarding essential health service delivery during the COVID-19 pandemic. We used a quasi-experimental difference-in-difference methodology to quantify the relationship between 192 countries’ progress towards UHC and GHS and those countries’ abilities to provide 12 essential childhood immunization services between 2015 and 2021. We used the 2019 UHC Service Coverage Index (SCI) to divide countries into a “high UHC group” (UHC SCI≥75) and the rest (UHC SCI 75), and similarly used the 2019 GHS Index (GHSI) to divide countries into a “high GHS group” (GHSI≥65) and the rest (GHSI<65). All analyses were adjusted for potential confounders. Countries with high UHC scores prevented a 1.14% (95% CI: 0.39%, 1.90%) reduction in immunization coverage across 2020 and 2021 whereas countries with high GHSI scores prevented a 1.10% (95% CI: 0.57%, 1.63%) reduction in immunization coverage over the same time period. The stratified DiD models showed that across both years, high UHC capacity needed to be augmented with high GHS capacity to prevent a decline in immunization coverage while high GHS alone was able to safeguard immunization coverage. This study found that greater progress towards both UHC and GHS capacities safeguarded essential health service delivery during the pandemic but only progress towards GHS capacity was both a necessary and likely sufficient element for yielding this protective effect. Our results call for strategic investments into both health agendas and future research into possible synergistic effects of the two health agendas.Understanding COVID-19 vaccine hesitancy in Meghalaya, India: Multiple correspondence and agglomerative hierarchical cluster analyses
AbstractKim, S., Sarkar, R., Kumar, S., Lewis, M. G., Tozan, Y., & Albert, S. (n.d.).Publication year
2024Journal title
PLOS Global Public HealthVolume
4Issue
2AbstractMeghalaya, a state in the northeastern region of India, had a markedly low vaccine uptake compared to the other states in the country when COVID-19 vaccines were being rolled out in 2021. This study aimed to characterize the distinct vaccine-hesitant subpopulations in healthcare and community settings in Meghalaya state in the early days of the vaccination program. We used data from a cross-sectional survey that was administered to 200 healthcare workers (HCWs) and 200 community members, who were a priori identified as 'vaccine- eligible' and 'vaccine-hesitant,' in Shillong city, Meghalaya, in May 2021. The questionnaire collected information on participants' sociodemographic characteristics, COVID-19 history, and presence of medical comorbidities. Participants were also asked to provide a dichotomous answer to a set of 19 questions, probing the reasons for their hesitancy towards COVID-19 vaccines. A multiple correspondence analysis, followed by an agglomerative hierarchical cluster analysis, was performed to identify the distinct clusters of vaccine-hesitant participants. We identified seven clusters: indecisive HCWs (n = 71), HCWs skeptical of COVID-19 and COVID-19 vaccines (n = 128), highly educated male tribal/clan leaders concerned about infertility and future pregnancies (n = 14), less educated adults influenced by leaders and family (n = 47), older adults worried about vaccine safety (n = 76), middle-aged adults without young children (n = 56), and highly educated ethnic/religious minorities with misinformation (n = 8). Across all the clusters, perceived logistical challenges associated with receiving the vaccine was identified as a common factor contributing to vaccine hesitancy. Our study findings provide valuable insights for local and state health authorities to effectively target distinct subgroups of vaccine-hesitant populations with tailored health messaging, and also call for a comprehensive approach to address the common drivers of vaccine hesitancy in communities with low vaccination rates."I decided in my heart I have to complete the sessions": A qualitative study on the acceptability of an evidence-based HIV risk reduction intervention among women engaged in sex work in Uganda
AbstractBahar, O. S., Nabunya, P., Nabayinda, J., Witte, S., Kiyingi, J., Nsubuga, E., Schriger, S., Nattabi, J., Mayo-Wilson, L. J., Nakigudde, J., Tozan, Y., & Ssewamala, F. M. (n.d.).Publication year
2023Journal title
PloS oneVolume
18Issue
1AbstractBackground The HIV burden remains a critical public health concern and women engaged in sex work [WESW] are at significantly higher risk compared to the general adult population. Similar to other sub-Saharan African countries, Uganda reports high rates of HIV prevalence among WESW. Yet, they have not been targeted by theory-informed HIV prevention intervention approaches. Methods We conducted semi-structured in-depth interviews with 20 WESW upon intervention completion to explore their experiences with an evidence-based HIV risk reduction intervention that was implemented as part of a combination intervention tested in a clinical trial in Uganda (2018-2023. Specifically, we explored their initial motivations and concerns for participating in the intervention, barriers and facilitators to attendance, and their feedback on specific intervention characteristics. Results The main expectations revolved around access to health-related information, including information on STIs, HIV, and PrEP as well as on how one can protect themselves while engaging in sex work. Initial concerns were around potential breach of confidentiality and fear of arrest. The main facilitators for session attendance were the motivation to learn healthrelated information, the attitude of facilitators, and the incentives received for participation, whereas main challenges were related to family commitments and work schedules. WESW appreciated the group format of the intervention and found the location and times of the intervention delivery acceptable. Discussion and conclusions Overall, our findings suggest that the HIV risk reduction intervention was appropriate and acceptable to WESW. Yet, WESW experience unique concerns and barriers that need to be accounted for when designing interventions targeting this population, especially in resource-limited settings where sex work is illegal and highly stigmatized.A Methodological Framework for Economic Evaluation of Operational Response to Vector-Borne Diseases Based on Early Warning Systems
AbstractTozan, Y., Sewe, M. O., Kim, S., & Rocklov, J. (n.d.).Publication year
2023Journal title
American Journal of Tropical Medicine and HygieneVolume
108Issue
3Page(s)
627-633AbstractDespite significant advances in improving the predictive models for vector-borne diseases, only a few countries have integrated an early warning system (EWS) with predictive and response capabilities into their disease surveillance systems. The limited understanding of forecast performance and uncertainties by decision-makers is one of the primary factors that precludes its operationalization in preparedness and response planning. Further, predictive models exhibit a decrease in forecast skill with longer lead times, a trade-off between forecast accuracy and timeliness and effectiveness of action. This study presents a methodological framework to evaluate the economic value of EWS-triggered responses from the health system perspective. Assuming an operational EWS in place, the framework makes explicit the trade-offs between forecast accuracy, timeliness of action, effectiveness of response, and costs, and uses the net benefit analysis, which measures the benefits of taking action minus the associated costs. Uncertainty in disease forecasts and other parameters is accounted for through probabilistic sensitivity analysis. The output is the probability distribution of the net benefit estimates at given forecast lead times. A non-negative net benefit and the probability of yielding such are considered a general signal that the EWS-triggered response at a given lead time is economically viable. In summary, the proposed framework translates uncertainties associated with disease forecasts and other parameters into decision uncertainty by quantifying the economic risk associated with operational response to vector-borne disease events of potential importance predicted by an EWS. The goal is to facilitate a more informed and transparent public health decision-making under uncertainty.Climate variability, socio-economic conditions and vulnerability to malaria infections in Mozambique 2016–2018: a spatial temporal analysis
AbstractArmando, C. J., Rocklöv, J., Sidat, M., Tozan, Y., Mavume, A. F., Bunker, A., & Sewes, M. O. (n.d.).Publication year
2023Journal title
Frontiers in Public HealthVolume
11AbstractBackground: Temperature, precipitation, relative humidity (RH), and Normalized Different Vegetation Index (NDVI), influence malaria transmission dynamics. However, an understanding of interactions between socioeconomic indicators, environmental factors and malaria incidence can help design interventions to alleviate the high burden of malaria infections on vulnerable populations. Our study thus aimed to investigate the socioeconomic and climatological factors influencing spatial and temporal variability of malaria infections in Mozambique. Methods: We used monthly malaria cases from 2016 to 2018 at the district level. We developed an hierarchical spatial–temporal model in a Bayesian framework. Monthly malaria cases were assumed to follow a negative binomial distribution. We used integrated nested Laplace approximation (INLA) in R for Bayesian inference and distributed lag nonlinear modeling (DLNM) framework to explore exposure-response relationships between climate variables and risk of malaria infection in Mozambique, while adjusting for socioeconomic factors. Results: A total of 19,948,295 malaria cases were reported between 2016 and 2018 in Mozambique. Malaria risk increased with higher monthly mean temperatures between 20 and 29°C, at mean temperature of 25°C, the risk of malaria was 3.45 times higher (RR 3.45 [95%CI: 2.37–5.03]). Malaria risk was greatest for NDVI above 0.22. The risk of malaria was 1.34 times higher (1.34 [1.01–1.79]) at monthly RH of 55%. Malaria risk reduced by 26.1%, for total monthly precipitation of 480 mm (0.739 [95%CI: 0.61–0.90]) at lag 2 months, while for lower total monthly precipitation of 10 mm, the risk of malaria was 1.87 times higher (1.87 [1.30–2.69]). After adjusting for climate variables, having lower level of education significantly increased malaria risk (1.034 [1.014–1.054]) and having electricity (0.979 [0.967–0.992]) and sharing toilet facilities (0.957 [0.924–0.991]) significantly reduced malaria risk. Conclusion: Our current study identified lag patterns and association between climate variables and malaria incidence in Mozambique. Extremes in climate variables were associated with an increased risk of malaria transmission, peaks in transmission were varied. Our findings provide insights for designing early warning, prevention, and control strategies to minimize seasonal malaria surges and associated infections in Mozambique a region where Malaria causes substantial burden from illness and deaths.Correlates of Intimate Partner Violence Among Young Women Engaged in Sex Work in Southern Uganda
AbstractNabayinda, J., Namirembe, R., Kizito, S., Nsubuga, E., Nabunya, P., Sensoy Bahar, O., Magorokosho, N., Kiyingi, J., Nattabi, J., Tozan, Y., Jennings Mayo-Wilson, L., Mwebembezi, A., Witte, S. S., & Ssewamala, F. M. (n.d.).Publication year
2023Journal title
Journal of Interpersonal ViolenceVolume
38Issue
19Page(s)
10749-10770AbstractIntimate partner violence (IPV) is a significant global public health problem that results in high social and economic costs to individuals and communities. Compared to women in the general population, women engaged in sex work (WESW) are more likely to experience physical, emotional, and sexual IPV. This study examines the correlates of IPV among young WESW with their intimate partners in Southern Uganda. We used baseline data from the Kyaterekera project, a 5 year NIH-funded longitudinal study aimed at reducing HIV risks among 542 WESW in Southern Uganda. To examine the factors associated with IPV, we fitted three separate multi-level Poisson regression models for physical, emotional, and sexual IPV, respectively. Average age was 31.4 years, and 54% of the women reported being victims of at least one form of IPV from their intimate partners. Model one assessed correlates of sexual IPV. Being married women (β =.71, 95% CI [0.24, 1.17]), divorced/separated/widowed (β =.52, [0.02, 1.02]), depressed (β =.04, [0.02, 0.05]), and having any sexually transmitted infections (STIs) (β =.58, [0.14, 1.01]) were associated with sexual IPV. Model two assessed correlates of physical IPV. Experience of childhood sexual abuse (β =.12, [0.04, 0.19]) was associated with an increase in physical IPV, and increasing age reduced its occurrence (β = −.02, [−0.04, −0.001]). Finally, model three assessed emotional IPV. Women with higher education (β =.49, [0.14, 0.85]) and symptoms of depression (β =.02, [0.001, 0.04]) had higher risks for emotional IPV. For WESW, IPV presents an additional potential pathway for HIV and STIs acquisition and transmission through a lack of negotiating power for safe sex. Efforts to reduce violence against WESW should be prioritized as a strategy for enhancing the well-being of WESW.Economic Abuse and Care-seeking Practices for HIV and Financial Support Services in Women Employed by Sex Work: A Cross-Sectional Baseline Assessment of a Clinical Trial Cohort in Uganda
AbstractJennings Mayo-Wilson, L., Yen, B. J., Nabunya, P., Bahar, O. S., Wright, B. N., Kiyingi, J., Filippone, P. L., Mwebembezi, A., Kagaayi, J., Tozan, Y., Nabayinda, J., Witte, S. S., & Ssewamala, F. M. (n.d.).Publication year
2023Journal title
Journal of Interpersonal ViolenceVolume
38Issue
1Page(s)
NP1920-NP1949AbstractEconomic hardship is a driver of entry into sex work, which is associated with high HIV risk. Yet, little is known about economic abuse in women employed by sex work (WESW) and its relationship to uptake of HIV prevention and financial support services. This study used cross-sectional baseline data from a multisite, longitudinal clinical trial that tests the efficacy of adding economic empowerment to traditional HIV risk reduction education on HIV incidence in 542 WESW. Mixed effects logistic and linear regressions were used to examine associations in reported economic abuse by demographic characteristics, sexual behaviors, HIV care-seeking, and financial care-seeking. Mean age was 31.4 years. Most WESW were unmarried (74%) and had less than primary school education (64%). 48% had savings, and 72% had debt. 93% reported at least one economic abuse incident. Common incidents included being forced to ask for money (80%), having financial information kept from them (61%), and being forced to disclose how money was spent (56%). WESW also reported partners/relatives spending money needed for bills (45%), not paying bills (38%), threatening them to quit their job(s) (38%), and using physical violence when earning income (24%). Married/partnered WESW (OR = 2.68, 95% CI:1.60–4.48), those with debt (OR = 1.70, 95% CI:1.04–2.77), and those with sex-work bosses (OR = 1.90, 95% CI:1.07–3.38) had higher economic abuse. Condomless sex (β = +4.43, p <.05) was higher among WESW experiencing economic abuse, who also had lower odds of initiating PrEP (OR =.39, 95% CI:.17–.89). WESW experiencing economic abuse were also more likely to ask for cash among relatives (OR = 2.36, 95% CI:1.13–4.94) or banks (OR = 2.12, 95% CI:1.11–4.03). The high prevalence of HIV and economic abuse in WESW underscores the importance of integrating financial empowerment in HIV risk reduction interventions for WESW, including education about economic abuse and strategies to address it. Programs focusing on violence against women should also consider economic barriers to accessing HIV prevention services.European projections of West Nile virus transmission under climate change scenarios
AbstractFarooq, Z., Sjödin, H., Semenza, J. C., Tozan, Y., Sewe, M. O., Wallin, J., & Rocklöv, J. (n.d.).Publication year
2023Journal title
One HealthVolume
16AbstractWest Nile virus (WNV), a mosquito-borne zoonosis, has emerged as a disease of public health concern in Europe. Recent outbreaks have been attributed to suitable climatic conditions for its vectors favoring transmission. However, to date, projections of the risk for WNV expansion under climate change scenarios is lacking. Here, we estimate the WNV-outbreaks risk for a set of climate change and socioeconomic scenarios. We delineate the potential risk-areas and estimate the growth in the population at risk (PAR). We used supervised machine learning classifier, XGBoost, to estimate the WNV-outbreak risk using an ensemble climate model and multi-scenario approach. The model was trained by collating climatic, socioeconomic, and reported WNV-infections data (2010−22) and the out-of-sample results (1950–2009, 2023–99) were validated using a novel Confidence-Based Performance Estimation (CBPE) method. Projections of area specific outbreak risk trends, and corresponding population at risk were estimated and compared across scenarios. Our results show up to 5-fold increase in West Nile virus (WNV) risk for 2040-60 in Europe, depending on geographical region and climate scenario, compared to 2000-20. The proportion of disease-reported European land areas could increase from 15% to 23-30%, putting 161 to 244 million people at risk. Across scenarios, Western Europe appears to be facing the largest increase in the outbreak risk of WNV. The increase in the risk is not linear but undergoes periods of sharp changes governed by climatic thresholds associated with ideal conditions for WNV vectors. The increased risk will require a targeted public health response to manage the expansion of WNV with climate change in Europe.Examining Changes in Sleep Duration Associated with the Onset of the COVID-19 Pandemic: Who is Sleeping and Who is Not?
AbstractBatool-Anwar, S., Robbins, R., Ali, S. H., Capasso, A., Foreman, J., Jones, A. M., Tozan, Y., DiClemente, R. J., & Quan, S. F. (n.d.).Publication year
2023Journal title
Behavioral MedicineVolume
49Issue
2Page(s)
162-171AbstractThe COVID-19 pandemic has resulted in social isolation and reports of insomnia. However, reports of changes in sleep duration and associated factors are few. To determine the impact of COVID-19 on changes in sleep behavior, data were analyzed from an online survey of adults recruited via social media that included questions asking whether the respondent slept less or more after the onset of the pandemic as well as self-reported sociodemographic and occupational information; beliefs about COVID-19; and responses pertaining to loneliness, anxiety, and depression. There were 5,175 respondents; 53.9% had a change in sleep duration.17.1% slept less and 36.7% slept more. Sleeping more was related to greater education, being single/divorced/separated, unemployed or a student. Being retired, divorced/separated or a homemaker, and living in the Mountain or Central time zones were associated with less sleep. Beliefs that COVID-19 would result in personal adverse consequences was associated with both more and less sleep. However, the strongest associations for both more and less sleep were seen with depression, anxiety, and loneliness. In summary, changes in sleep duration since the start of the COVID-19 pandemic were highly prevalent among social media users and were associated with several sociodemographic factors and beliefs that COVID-19 would have adverse personal impacts. However, the strongest associations occurred with worse mental health suggesting that improvements may occur with better sleep. Supplemental data for this article is available online at https://doi.org/10.1080/08964289.2021.2002800.Impact, healthcare utilization and costs of travel-associated mosquito-borne diseases in international travellers: a prospective study
AbstractTozan, Y., Headley, T. Y., Javelle, E., Gautret, P., Grobusch, M., De Pijper, C., Asgeirsson, H., Chen, L. H., Bourque, D., Menéndez, M. D., Moro, L., Gobbi, F., Sánchez-Montalvá, A., Connor, B. A., Matteelli, A., Crosato, V., Huits, R., Libman, M., & Hamer, D. H. (n.d.).Publication year
2023Journal title
Journal of Travel MedicineVolume
30Issue
7AbstractBackground: International travellers frequently acquire infectious diseases whilst travelling, yet relatively little is known about the impact and economic burden of these illnesses on travellers. We conducted a prospective exploratory costing study on adult returning travellers with falciparum malaria, dengue, chikungunya or Zika virus. Methods: Patients were recruited in eight Travel and Tropical Medicine clinics between June 2016 and March 2020 upon travellers’ first contact with the health system in their country of residence. The patients were presented with a structured 52-question self-administered questionnaire after full recovery to collect information on patients’ healthcare utilization and out-of-pocket costs both in the destination and home country, and about income and other financial losses due to the illness. Results: A total of 134 patients participated in the study (malaria, 66; dengue, 51; chikungunya, 8; Zika virus, 9; all fully recovered; median age 40; range 18–72 years). Prior to travelling, 42% of patients reported procuring medical evacuation insurance. Across the four illnesses, only 7% of patients were hospitalized abroad compared with 61% at home. Similarly, 15% sought ambulatory services whilst abroad compared with 61% at home. The average direct out-of-pocket hospitalization cost in the destination country (USD $2236; range: $108–$5160) was higher than the direct out-of-pocket ambulatory cost in the destination country (USD $327; range: $0–$1560), the direct out-of-pocket hospitalization cost at home (USD $35; range: $0–$120) and the direct out-of-pocket ambulatory costs at home (US$45; range: $0–$192). Respondents with dengue or malaria lost a median of USD $570 (Interquartile range [IQR] 240–1140) and USD $240 (IQR 0–600), respectively, due to their illness, whilst those with chikungunya and Zika virus lost a median of USD $2400 (IQR 1200–3600) and USD $1500 (IQR 510–2625), respectively. Conclusion: Travellers often incur significant costs due to travel-acquired diseases. Further research into the economic impact of these diseases on travellers should be conducted.Predicting the dengue cluster outbreak dynamics in Yogyakarta, Indonesia: a modelling study
AbstractRamadona, A. L., Tozan, Y., Wallin, J., Lazuardi, L., Utarini, A., & Rocklöv, J. (n.d.).Publication year
2023Journal title
The Lancet Regional Health - Southeast AsiaVolume
15AbstractBackground: Human mobility and climate conditions are recognised key drivers of dengue transmission, but their combined and individual role in the local spatiotemporal clustering of dengue cases is not well understood. This study investigated the effects of human mobility and weather conditions on dengue risk in an urban area in Yogyakarta, Indonesia. Methods: We established a Bayesian spatiotemporal model for neighbourhood outbreak prediction and evaluated the performances of two different approaches for constructing an adjacency matrix: one based on geographical proximity and the other based on human mobility patterns. We used population, weather conditions, and past dengue cases as predictors using a flexible distributed lag approach. The human mobility data were estimated based on proxies from social media. Unseen data from February 2017 to January 2020 were used to estimate the one-month ahead prediction accuracy of the model. Findings: When human mobility proxies were included in the spatial covariance structure, the model fit improved in terms of the log score (from 1.748 to 1.561) and the mean absolute error (from 0.676 to 0.522) based on the validation data. Additionally, showed only few observations outside the credible interval of predictions (1.48%) and weather conditions were not found to contribute additionally to the clustering of cases at this scale. Interpretation: The study shows that it is possible to make highly accurate predictions of the within-city cluster dynamics of dengue using mobility proxies from social media combined with disease surveillance data. These insights are important for proactive and timely outbreak management of dengue. Funding: Swedish Research Council Formas, Umeå Centre for Global Health Research, Swedish Council for Working Life and Social Research, Swedish research council VINNOVA and Alexander von Humboldt Foundation (Germany).Private Payer-Negotiated Rates for FDA-Approved Head and Neck Cancer Immunotherapy and Chemotherapy Agents
AbstractTalwar, A., Kim, S., Yu, S., Samant, S., Tozan, Y., & Givi, B. (n.d.).Publication year
2023Journal title
Otolaryngology - Head and Neck SurgeryVolume
169Issue
4Page(s)
954-961AbstractObjective: To quantify the price that private payers pay hospitals for head and neck squamous cell carcinoma (HNSCC) treatments and identify hospital-level factors associated with price variation. Study Design: Cross-sectional study. Setting: Price transparency files. Methods: Files from the top 50 hospitals in otolaryngology according to the US News and World Report were analyzed between December 2021 and June 2022. This study analyzed the following Food and Drug Administration-approved HNSCC therapies: pembrolizumab, nivolumab, cetuximab, cisplatin, carboplatin, and paclitaxel. Results: Twenty-four (48%) hospitals reported prices for at least 1 medication in our sample. Newer biologics were significantly more expensive than traditional chemotherapeutic agents. Given approved medication regimens, all biologics in our sample have similar annual costs. Price markups over acquisition costs ranged between 109% (pembrolizumab, nivolumab) and 530% for carboplatin. Across hospitals, prices varied the most for paclitaxel, the cheapest medication in our sample, and prices varied the least for pembrolizumab the most expensive medication in our sample. Hospital 340B status and geographic location in the northeast/west are associated with lower price markups. Conclusion: Price nondisclosure remains a significant problem among hospitals. Newer biological medications are more expensive when compared to traditional chemotherapeutic agents. Prices vary significantly across hospitals, with lower price markups observed in 340B hospitals as well as hospitals located in the geographic northeast and west. It remains to be seen if price transparency will lead to more uniform pricing or lower costs of treatments.Self-Reported Adherence to Antiretroviral Therapy (ART) Among Women Engaged in Commercial Sex Work in Southern Uganda
AbstractKiyingi, J., Nabunya, P., Kizito, S., Nabayinda, J., Nsubuga, E., Bahar, O. S., Jennings Mayo-Wilson, L., Namuwonge, F., Nattabi, J., Magorokosho, N., Tozan, Y., Witte, S. S., & Ssewamala, F. M. (n.d.).Publication year
2023Journal title
AIDS and BehaviorVolume
27Issue
3Page(s)
1004-1012AbstractWe examined the correlates of self-reported adherence to antiretroviral therapy (ART) among women engaged in commercial sex work (WESW) in Uganda. We used baseline data from a longitudinal study, which recruited 542 WESW in Southern Uganda. We used nested regression models to determine the individual and family, and economic level correlates of self-reported adherence. Study findings show that older age (OR = 1.07, 95% CI = 1.013, 1.139), secondary education (OR = 2.01, 95% CI = 1.306, 3.084), large household size (OR = 1.08, 95% CI = 1.020, 1.136), high family cohesion (OR = 1.06, 95% CI = 1.052, 1.065), and high financial self-efficacy (OR = 1.07, 95% CI = 1.006, 1.130) were associated with good self-reported adherence to ART. Married women (OR=-0.39, 95% CI = 0.197, 0.774), depression (OR = 0.85, 95% CI = 0.744, 0.969), alcohol use (OR = 0.72, 95% CI = 0.548, 0.954), ever been arrested (OR = 0.58, 95% CI = 0.341, 0.997), and high household assets ownership (OR = 0.48, 95% CI = 0.313, 0.724) were associated with poor self-reported adherence to ART. Findings suggest a need to adopt a multi-level approach to address gaps in ART adherence among WESW.The effectiveness of malaria camps as part of the malaria control program in Odisha, India
AbstractOmpad, D. C., Padhan, T. K., Kessler, A., Tozan, Y., Jones, A. M., Van Eijk, A. M., Sullivan, S. A., Haque, M. A., Pradhan, M. M., Mohanty, S., Carlton, J. M., & Sahu, P. K. (n.d.).Publication year
2023Journal title
Scientific reportsVolume
13Issue
1AbstractDurgama Anchalare Malaria Nirakaran (DAMaN) is a multi-component malaria intervention for hard-to-reach villages in Odisha, India. The main component, malaria camps (MCs), consists of mass screening, treatment, education, and intensified vector control. We evaluated MC effectiveness using a quasi-experimental cluster-assigned stepped-wedge study with a pretest–posttest control group in 15 villages: six immediate (Arm A), six delayed (Arm B), and three previous interventions (Arm C). The primary outcome was PCR + Plasmodium infection prevalence. The time (i.e., baseline vs. follow-up 3) x study arm interaction term shows that there were statistically significant lower odds of PCR + Plasmodium infection in Arm A (AOR = 0.36, 95% CI = 0.17, 0.74) but not Arm C as compared to Arm B at the third follow-up. The cost per person ranged between US$3–8, the cost per tested US$4–9, and the cost per treated US$82–1,614, per camp round. These results suggest that the DAMaN intervention is a promising and financially feasible approach for malaria control."I expected little, although I learned a lot": perceived benefits of participating in HIV risk reduction sessions among women engaged in sex work in Uganda
AbstractSensoy Bahar, O., Nabunya, P., Nabayinda, J., Witte, S. S., Kiyingi, J., Mayo-Wilson, L. J., Filippone, P., Yang, L. S., Nakigudde, J., Tozan, Y., & Ssewamala, F. M. (n.d.).Publication year
2022Journal title
BMC Women's HealthVolume
22Issue
1AbstractBackground: The global HIV burden remains a public health concern. Women engaged in sex work (WESW) are at higher risk of acquiring HIV compared to the general adult population. Uganda reports high rates of HIV prevalence among WESW. While WESW in Uganda have long been the subject of surveillance studies, they have not been targeted by theory-informed HIV prevention intervention approaches. In this study, we explored the perceived benefits of an evidence-based HIV risk reduction intervention that was implemented as part of a combination intervention tested in a clinical trial in Uganda. Methods: As part of a larger randomized clinical trial, we conducted semi-structured in-depth interviews with 20 WESW selected using a stratified purposive sampling. All interviews were conducted in Luganda, language spoken in the study area, and audio-recorded. They were transcribed verbatim and translated to English. Thematic analysis was used to analyze the data. Results: WESW’s narratives focused on: (1) condom use; (2) alcohol/drug consumption; (3) PrEP use; (4) “handling” customers; and (5) "massaging” customers. WESW agreed that male condom was one of the important learning points for them and planned to continue using them while female condoms were received with mixed reactions. Many women appreciated receiving information about the risks of consuming alcohol and drugs, and discussed how they reduced/ eliminated their consumption. PrEP information was appreciated though identified by fewer WESW. Handling a client was discussed as a helpful strategy for safer sex through improved ability to convince customers to use condoms or avoiding sex. Massaging was also beneficial to avoid penetrative sex, but similar to female condom, massaging also yielded mixed perceptions. Conclusion: WESW found the intervention beneficial and described ways in which it improved their ability to engage in safer sex and stay healthy. The fact that WESW identified other strategies beyond condom use as helpful underlines the importance of adopting a comprehensive approach to behavioral interventions targeting HIV prevention even when combined with other interventions. Additionally, WESW’s narratives suggest that incorporating the tenets of social cognitive theory and harm reduction approaches in HIV prevention among this population can result in risk behavior change.A Multilevel Integrated Intervention to Reduce the Impact of HIV Stigma on HIV Treatment Outcomes Among Adolescents Living With HIV in Uganda: Protocol for a Randomized Controlled Trial
AbstractMutumba, M., Ssewamala, F., Namirembe, R., Bahar, O. S., Nabunya, P., Neilands, T., Tozan, Y., Namuwonge, F., Nattabi, J., Laker, P. A., Mukasa, B., & Mwebembezi, A. (n.d.).Publication year
2022Journal title
JMIR Research ProtocolsVolume
11Issue
10AbstractBackground: HIV stigma remains a formidable barrier to HIV treatment adherence among school-attending adolescents living with HIV, owing to high levels of HIV stigma within schools, rigid school structures and routines, lack of adherence support, and food insecurity. Thus, this protocol paper presents an evidence-informed multilevel intervention that will simultaneously address family- and school-related barriers to HIV treatment adherence and care engagement among adolescents living with HIV attending boarding schools in Uganda. Objective: The proposed intervention-Multilevel Suubi (MSuubi)-has the following objectives: examine the impact of M-Suubi on HIV viral suppression (primary outcome) and adherence to HIV treatment, including keeping appointments, pharmacy refills, pill counts, and retention in care; examine the effect of M-Suubi on HIV stigma (internalized, anticipated, and enacted), with secondary analyses to explore hypothesized mechanisms of change (eg, depression) and intervention mediation; assess the cost and cost-effectiveness of each intervention condition; and qualitatively examine participants' experiences with HIV stigma, HIV treatment adherence, and intervention and educators' attitudes toward adolescents living with HIV and experiences with group-based HIV stigma reduction for educators, and program or policy implementation after training. Methods: MSuubi is a 5-year multilevel mixed methods randomized controlled trial targeting adolescents living with HIV aged 10 to 17 years enrolled in a primary or secondary school with a boarding section. This longitudinal study will use a 3-arm cluster randomized design across 42 HIV clinics in southwestern Uganda. Participants will be randomized at the clinic level to 1 of the 3 study conditions (n=14 schools; n=280 students per study arm). These include the bolstered usual care (consisting of the literature on antiretroviral therapy adherence promotion and stigma reduction), multiple family groups for HIV stigma reduction plus family economic empowerment (MFG-HIVSR plus FEE), and Group-based HIV stigma reduction for educators (GED-HIVSR). Adolescents randomized to the GED-HIVSR treatment arm will also receive the MFG-HIVSR plus FEE treatment. MSuubi will be provided for 20 months, with assessments at baseline and 12, 24, and 36 months. Results: This study was funded in September 2021. Participant screening and recruitment began in April 2022, with 158 dyads enrolled as of May 2022. Dissemination of the main study findings is anticipated in 2025. Conclusions: MSuubi will assess the effects of a combined intervention (family-based economic empowerment, financial literacy education, and school-based HIV stigma) on HIV stigma among adolescents living with HIV in Uganda. The results will expand our understanding of effective intervention strategies for reducing stigma among HIV-infected and noninfected populations in Uganda and improving HIV treatment outcomes among adolescents living with HIV in sub-Saharan Africa.