Yesim Tozan
Yesim Tozan
Assistant Professor of Global Health
-
Professional overview
-
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.”
-
Education
-
BS, Environmental Engineering, Istanbul Technical University, TurkeyMS, Environmental Technology, Bogazici University, TurkeyMA, Public Affairs, Princeton University, Princeton, NJPhD, Public Affairs, Princeton University, Princeton, NJ
-
Areas of research and study
-
Cost EffectivenessCost-effective Health Programs and PoliciesEconomic EvaluationHealth EconomicsInfectious DiseasesPrevention Interventions
-
Publications
Publications
"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.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?
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 SurgeryAbstractObjective: 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."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.Adapting a tobacco cessation treatment intervention and implementation strategies to enhance implementation effectiveness and clinical outcomes in the context of HIV care in Vietnam: a case study
AbstractShelley, D., Alvarez, G. G., Nguyen, T., Nguyen, N., Goldsamt, L., Cleland, C., Tozan, Y., Shuter, J., & Armstrong-Hough, M. (n.d.).Publication year
2022Journal title
Implementation science communicationsVolume
3Issue
1Page(s)
112AbstractBACKGROUND: Smoking rates remain high in Vietnam, particularly among people living with HIV/AIDS (PLWH), but tobacco cessation services are not available in outpatient HIV clinics (OPCs). The research team is conducting a type II hybrid randomized controlled trial (RCT) comparing the cost-effectiveness of three tobacco cessation interventions among PLWH receiving care in HIV clinics in Vietnam. The study is simultaneously evaluating the implementation processes and outcomes of strategies aimed at increasing the implementation of tobacco dependence treatment (TDT) in the context of HIV care. This paper describes the systematic, theory-driven process of adapting intervention components and implementation strategies with demonstrated effectiveness in high-income countries, and more recently in Vietnam, to a new population (i.e., PLWH) and new clinical setting, prior to launching the trial.METHODS: Data collection and analyses were guided by two implementation science frameworks and the socio-ecological model. Qualitative interviews were conducted with 13 health care providers and 24 patients in three OPCs. Workflow analyses were conducted in each OPC. Qualitative data were analyzed using rapid qualitative analysis procedures. Based on findings, components of the intervention and implementation strategies were adapted, followed by a 3-month pilot study in one OPC with 16 patients randomized to one of two intervention arms.RESULTS: The primary adaptations included modifying the TDT intervention counseling content to address barriers to quitting among PLWH and Vietnamese sociocultural norms that support smoking cessation. Implementation strategies (i.e., training and system changes) were adapted to respond to provider- and clinic-level determinants of implementation effectiveness (e.g., knowledge gaps, OPC resource constraints, staffing structure, compatibility).CONCLUSIONS: Adaptations were facilitated through a mixed method, stakeholder (patient and health care provider, district health leader)-engaged evaluation of context-specific influences on intervention and implementation effectiveness. This data-driven approach to refining and adapting components aimed to optimize intervention effectiveness and implementation in the context of HIV care. Balancing pragmatism with rigor through the use of rapid analysis procedures and multiple methods increased the feasibility of the adaptation process.TRIAL REGISTRATION: ClinicalTrials.gov NCT05162911 . Registered on December 16, 2021.Advancing scalability and impacts of a teacher training program for promoting child mental health in Ugandan primary schools: protocol for a hybrid-type II effectiveness-implementation cluster randomized trial
AbstractHuang, K. Y., Nakigudde, J., Kisakye, E. N., Sentongo, H., Dennis-Tiwary, T. A., Tozan, Y., Park, H., & Brotman, L. M. (n.d.).Publication year
2022Journal title
International Journal of Mental Health SystemsVolume
16Issue
1AbstractBackground: Children in low-and-middle-income countries (LMICs) are facing tremendous mental health challenges. Numerous evidence-based interventions (EBIs) have been adapted to LMICs and shown effectiveness in addressing the needs, but most EBIs have not been adopted widely using scalable and sustainable implementation models that leverage and strengthen existing structures. There is a need to apply implementation science methodology to study strategies to effectively scale-up EBIs and sustain the practices in LMICs. Through a cross-sector collaboration, we are carrying out a second-generation investigation of implementation and effectiveness of a school-based mental health EBI, ParentCorps Professional Development (PD), to scale-up and sustain the EBI in Uganda to promote early childhood students’ mental health. Our previous studies in Uganda supported that culturally adapted PD resulted in short-term benefits for classrooms, children, and families. However, our previous implementation of PD was relied on mental health professionals (MHPs) to provide PD to teachers. Because of the shortage of MHPs in Uganda, a new scalable implementation model is needed to provide PD at scale. Objectives: This study tests a new scalable and sustainable PD implementation model and simultaneously studies the effectiveness. This paper describes use of collaboration, task-shifting, and Train-the-Trainer strategies for scaling-up PD, and protocol for studying the effectiveness-implementation of ParentCorps-PD for teachers in urban and rural Ugandan schools. We will examine whether the new scale-up implementation approach will yield anticipated impacts and investigate the underlying effectiveness-implementation mechanisms that contribute to success. In addition, considering the effects of PD on teachers and students will influence by teacher wellness. This study also examines the added value (i.e. impact and costs) of a brief wellness intervention for teachers and students. Methods: Using a hybrid-type II effectiveness-implementation cluster randomized controlled trial (cRCT), we will randomize 36 schools (18 urban and 18 rural) with 540 teachers and nearly 2000 families to one of three conditions: PD + Teacher-Wellness (PDT), PD alone (PD), and Control. Primary effectiveness outcomes are teachers’ use of mental health promoting strategies, teacher stress management, and child mental health. The implementation fidelity/quality for the scale-up model will be monitored. Mixed methods will be employed to examine underlying mechanisms of implementation and impact as well as cost-effectiveness. Discussion: This research will generate important knowledge regarding the value of an EBI in urban and rural communities in a LMIC, and efforts toward supporting teachers to prevent and manage early signs of children’s mental health issues as a potentially cost-effective strategy to promote child population mental health in low resource settings. Trial Registration: This trial was registered with ClinicalTrials.gov (registration number: NCT04383327; https://clinicaltrials.gov/ct2/show/NCT04383327) on May13, 2020.Assessing the associations between Aedes larval indices and dengue risk in Kalutara district, Sri Lanka: a hierarchical time series analysis from 2010 to 2019
AbstractLiyanage, P., Tozan, Y., Tissera, H. A., Overgaard, H. J., & Rocklöv, J. (n.d.).Publication year
2022Journal title
Parasites and VectorsVolume
15Issue
1AbstractBackground: Dengue is a major public health problem in Sri Lanka. Aedes vector surveillance and monitoring of larval indices are routine, long-established public health practices in the country. However, the association between Aedes larval indices and dengue incidence is poorly understood. It is crucial to evaluate lagged effects and threshold values of Aedes larval indices to set pragmatic targets for sustainable vector control interventions. Methods: Monthly Aedes larval indices and dengue cases in all 10 Medical Officer of Health (MOH) divisions in Kalutara district were obtained from 2010 to 2019. Using a novel statistical approach, a distributed lag non-linear model and a two-staged hierarchical meta-analysis, we estimated the overall non-linear and delayed effects of the Premise Index (PI), Breteau Index (BI) and Container Index (CI) on dengue incidence in Kalutara district. A set of MOH division-specific variables were evaluated within the same meta-analytical framework to determine their moderator effects on dengue risk. Using generalized additive models, we assessed the utility of Aedes larval indices in predicting dengue incidence. Results: We found that all three larval indices were associated with dengue risk at a lag of 1 to 2 months. The relationship between PI and dengue was homogeneous across MOH divisions, whereas that with BI and CI was heterogeneous. The threshold values of BI, PI and CI associated with dengue risk were 2, 15 and 45, respectively. All three indices showed a low to moderate accuracy in predicting dengue risk in Kalutara district. Conclusions: This study showed the potential of vector surveillance information in Kalutara district in developing a threshold-based, location-specific early warning system with a lead time of 2 months. The estimated thresholds are nonetheless time-bound and may not be universally applicable. Whenever longitudinal vector surveillance data areavailable, the methodological framework we propose here can be used to estimate location-specific Aedes larval index thresholds in any other dengue-endemic setting. Graphical Abstract: [Figure not available: see fulltext.]Effect of El Niño–Southern Oscillation and local weather on Aedes dvector activity from 2010 to 2018 in Kalutara district, Sri Lanka: a two-stage hierarchical analysis
AbstractLiyanage, P., Tozan, Y., Overgaard, H. J., Aravinda Tissera, H., & Rocklöv, J. (n.d.).Publication year
2022Journal title
The Lancet Planetary HealthVolume
6Issue
7Page(s)
e577-e585AbstractBackground: Dengue, transmitted by Aedes mosquitoes, is a major public health problem in Sri Lanka. Weather affects the abundance, feeding patterns, and longevity of Aedes vectors and hence the risk of dengue transmission. We aimed to quantify the effect of weather variability on dengue vector indices in ten Medical Officer of Health (MOH) divisions in Kalutara, Sri Lanka. Methods: Monthly weather variables (rainfall, temperature, and Oceanic Niño Index [ONI]) and Aedes larval indices in each division in Kalutara were obtained from 2010 to 2018. Using a distributed lag non-linear model and a two-stage hierarchical analysis, we estimated and compared division-level and overall relationships between weather and premise index, Breteau index, and container index. Findings: From Jan 1, 2010, to Dec 31, 2018, three El Niño events (2010, 2015–16, and 2018) occurred. Increasing monthly cumulative rainfall higher than 200 mm at a lag of 0 months, mean temperatures higher than 31·5°C at a lag of 1–2 months, and El Niño conditions (ie, ONI >0·5) at a lag of 6 months were associated with an increased relative risk of premise index and Breteau index. Container index was found to be less sensitive to temperature and ONI, and rainfall. The associations of rainfall and temperature were rather homogeneous across divisions. Interpretation: Both temperature and ONI have the potential to serve as predictors of vector activity at a lead time of 1–6 months, while the amount of rainfall could indicate the magnitude of vector prevalence in the same month. This information, along with knowledge of the distribution of breeding sites, is useful for spatial risk prediction and implementation of effective Aedes control interventions. Funding: None.Employment conditions as barriers to the adoption of COVID-19 mitigation measures: how the COVID-19 pandemic may be deepening health disparities among low-income earners and essential workers in the United States
AbstractCapasso, A., Kim, S., Ali, S. H., Jones, A. M., DiClemente, R. J., & Tozan, Y. (n.d.).Publication year
2022Journal title
BMC public healthVolume
22Issue
1AbstractBackground: The COVID-19 pandemic has disproportionately impacted economically-disadvantaged populations in the United States (US). Precarious employment conditions may contribute to these disparities by impeding workers in such conditions from adopting COVID-19 mitigation measures to reduce infection risk. This study investigated the relationship between employment and economic conditions and the adoption of COVID-19 protective behaviors among US workers during the initial phase of the COVID-19 pandemic. Methods: Employing a social media advertisement campaign, an online, self-administered survey was used to collect data from 2,845 working adults in April 2020. Hierarchical generalized linear models were performed to assess the differences in engagement with recommended protective behaviors based on employment and economic conditions, while controlling for knowledge and perceived threat of COVID-19, as would be predicted by the Health Belief Model (HBM). Results: Essential workers had more precarious employment and economic conditions than non-essential workers: 67% had variable income; 30% did not have paid sick leave; 42% had lost income due to COVID-19, and 15% were food insecure. The adoption of protective behaviors was high in the sample: 77% of participants avoided leaving home, and 93% increased hand hygiene. Consistent with the HBM, COVID-19 knowledge scores and perceived threat were positively associated with engaging in all protective behaviors. However, after controlling for these, essential workers were 60% and 70% less likely than non-essential workers, who by the nature of their jobs cannot stay at home, to stay at home and increase hand hygiene, respectively. Similarly, participants who could not afford to quarantine were 50% less likely to avoid leaving home (AOR: 0.5; 95% CI: 0.4, 0.6) than those who could, whereas there were no significant differences concerning hand hygiene. Conclusions: Our findings are consistent with the accumulating evidence that the employment conditions of essential workers and other low-income earners are precarious, that they have experienced disproportionately higher rates of income loss during the initial phase of the COVID-19 pandemic and face significant barriers to adopting protective measures. Our findings underscore the importance and need of policy responses focusing on expanding social protection and benefits to prevent the further deepening of existing health disparities in the US.Knowledge, beliefs, mental health, substance use, and behaviors related to the COVID-19 pandemic among US adults: a national online survey
PrEP acceptability and initiation among women engaged in sex work in Uganda: Implications for HIV prevention
AbstractWitte, S. S., Filippone, P., Ssewamala, F. M., Nabunya, P., Bahar, O. S., Mayo-Wilson, L. J., Namuwonge, F., Damulira, C., Tozan, Y., Kiyingi, J., Nabayinda, J., Mwebembezi, A., Kagaayi, J., & McKay, M. (n.d.).Publication year
2022Journal title
EClinicalMedicineVolume
44AbstractBackground: Women engaged in sex work (WESW) are disproportionately affected by HIV. In Uganda, HIV prevalence among WESW is estimated at 37%, accounting for 18% of all new infections in the country. WESW experience poverty, gender-based violence, and other issues that reduce their power and limit their ability to negotiate condom use. Female-controlled strategies, including pre-exposure prophylaxis (PrEP), may afford women more transmission protection, but barriers to access and use persist. This cross-sectional study examined baseline PrEP acceptability and initiation among WESW recently enrolled in a randomized clinical trial in Uganda to test the impact of a combination HIV risk reduction and economic empowerment intervention on sexual risk outcomes (clinicaltrials.gov, NCT03583541). Methods: A total of 542 WESW from 19 high HIV-prevalent geographical areas were enrolled in the Kyaterekera study between June 2019 and March 2020. Women were eligible for the study if they: (1) were age 18 or over; (2) reported engagement in transactional sex (a sex act in exchange for pay) in the past 30 days; and (3) reported engagement in one or more episodes of unprotected sex in the past 30 days. Women completed a baseline assessment, were tested for HIV and other sexually transmitted infections (STIs) at enrollment, and were connected with antiretroviral therapy (ART), STI treatment, or PrEP, based on need and interest. Descriptive statistics examined baseline data on PrEP acceptability and initiation. Independent variables (i.e. years in sex work, recent sexual coercion, perceived HIV and sex work stigmas, harmful alcohol use, barriers to medical care, and social support) were derived from the empirical literature and women's self-report. Bivariate analysis was performed to test associations between main effects of these variables. Using binomial logistic regression, predictive models were evaluated for two distinct outcomes—PrEP acceptability and PrEP initiation/uptake. Findings: At baseline, 59% of women (n = 322) tested HIV negative. Among WESW testing negative, 11% (n = 36) were already PrEP enrolled. Most women reported willingness to use PrEP (n = 317; 91%). Slightly over half of WESW not already on PrEP agreed to initiate PrEP (n = 158; 55%). Logistic regression models demonstrate that acceptability of or willingness to use PrEP was significantly associated with fewer years engaged in sex work (AOR= ·18, 95% CI 0·05-·66, p<·01) and greater perceived social support from family (AOR= 1·39, 95% CI 1·03 -1.88, p<·05). PrEP initiation was negatively associated with greater perceived social support from friends (AOR=·81, 95% CI ·68–0·97, p<·05) and positively associated with higher perceived stigma due to sex work among family members (AOR=2·20, 95% CI 1·15–4·22, p<·05). Interpretation: Despite endorsing PrEP use, many WESW remain reluctant to use it. This gap in prevention practice highlights the heart of a failing PrEP prevention cascade. Findings point to the important role family and friend support may play in destigmatizing sex work and PrEP use for women. Social and structural-level efforts are needed to improve educational messaging and to integrate positive messaging into health promotion campaigns for women and their families, while also working toward decriminalizing sex work. Funding: This paper was made possible with funding from United States National Institute of Mental Health (Grant number: R01MH116768).Prevalence and predictors of HIV and sexually transmitted infections among vulnerable women engaged in sex work: Findings from the Kyaterekera Project in Southern Uganda
AbstractKiyingi, J., Nabunya, P., Bahar, O. S., Mayo-Wilson, L. J., Tozan, Y., Nabayinda, J., Namuwonge, F., Nsubuga, E., Kizito, S., Nattabi, J., Nakabuye, F., Kagayi, J., Mwebembezi, A., Witte, S. S., & Ssewamala, F. M. (n.d.).Publication year
2022Journal title
PloS oneVolume
17Issue
9AbstractIntroduction Women engaged in sex work (WESW) have an elevated risk of the human immunodeficiency virus (HIV) and sexually transmitted infections (STI). Estimates are three times higher than the general population. Understanding the predictors of HIV and STI among WESW is crucial in developing more focused HIV and STI prevention interventions among this population. The study examined the prevalence and predictors of HIV and STI among WESW in the Southern part of Uganda. Methodology Baseline data from the Kyaterekera study involving 542 WESW (ages 18–55) recruited from 19 HIV hotspots in the greater Masaka region in Uganda was utilized. HIV and STI prevalence was estimated using blood and vaginal fluid samples bioassay. Hierarchical regression models were used to determine the predictors of HIV and STI among WESW. Results Of the total sample, 41% (n = 220) were found to be HIV positive; and 10.5% (n = 57) tested positive for at least one of the three STI (Neisseria gonorrhoeae, Chlamydia trachomatis and Trichomonas vaginalis) regardless of their HIV status. Older age (b = 0.09, 95%CI = 0.06, 0.13, p≤0.001), lower levels of education (b = -0.79, 95%CI = -1.46, -0.11, p≤0.05), fewer numbers of children in the household (b = -0.18, 95%CI = -0.36, -0.01), p≤0.05), location (i.e., fishing village (b = 0.51, 95%CI = 0.16, 0.85, p≤0.01) or small town (b = -0.60, 95% CI = -0.92, -0.28, p≤0.001)), drug use (b = 0.58, 95%CI = 0.076, 1.08, p≤0.05) and financial self-efficacy (b = 0.05, 95%CI = -0.10, 0.00, p≤0.05), were associated with the risk of HIV infections among WESW. Domestic violence attitudes (b = -0.24, 95%CI = -0.42, -0.07, p≤0.01) and financial distress (b = -0.07, 95%CI = -0.14, -0.004, p≤0.05) were associated with the risk of STI infection among WESW. Conclusion Study findings show a high prevalence of HIV among WESW compared to the general women population. Individual and family level, behavioural and economic factors were associated with increased HIV and STI infection among WESW. Therefore, there is a need for WESW focused HIV and STI risk reduction and economic empowerment interventions to reduce these burdens.Universal healthcare coverage and health service delivery before and during the COVID- 19 pandemic: A difference-in-difference study of childhood immunization coverage from 195 countries
AbstractKim, S., Headley, T. Y., & Tozan, Y. (n.d.).Publication year
2022Journal title
PLoS MedicineVolume
19Issue
8AbstractBackground Several studies have indicated that universal health coverage (UHC) improves health service utilization and outcomes in countries. These studies, however, have primarily assessed UHC's peacetime impact, limiting our understanding of UHC's potential protective effects during public health crises such as the Coronavirus Disease 2019 (COVID-19) pandemic. We empirically explored whether countries' progress toward UHC is associated with differential COVID-19 impacts on childhood immunization coverage. Methods and findings Using a quasi-experimental difference-in-difference (DiD) methodology, we quantified the relationship between UHC and childhood immunization coverage before and during the COVID-19 pandemic. The analysis considered 195 World Health Organization (WHO) member states and their ability to provision 12 out of 14 childhood vaccines between 2010 and 2020 as an outcome. We used the 2019 UHC Service Coverage Index (UHC SCI) to divide countries into a "high UHC index"group (UHC SCI ≥80) and the rest. All analyses included potential confounders including the calendar year, countries' income group per the World Bank classification, countries' geographical region as defined by WHO, and countries' preparedness for an epidemic/pandemic as represented by the Global Health Security Index 2019. For robustness, we replicated the analysis using a lower cutoff value of 50 for the UHC index. A total of 20,230 country-year observations were included in the study. The DiD estimators indicated that countries with a high UHC index (UHC SCI ≥80, n = 35) had a 2.70% smaller reduction in childhood immunization coverage during the pandemic year of 2020 as compared to the countries with UHC index less than 80 (DiD coefficient 2.70; 95% CI: 0.75, 4.65; p-value = 0.007). This relationship, however, became statistically nonsignificant at the lower cutoff value of UHC SCI <50 (n = 60). The study's primary limitation was scarce data availability, which restricted our ability to account for confounders and to test our hypothesis for other relevant outcomes. Conclusions We observed that countries with greater progress toward UHC were associated with significantly smaller declines in childhood immunization coverage during the pandemic. This identified association may potentially provide support for the importance of UHC in building health system resilience. Our findings strongly suggest that policymakers should continue to advocate for achieving UHC in coming years.What predicts people’s belief in COVID-19 misinformation? A retrospective study using a nationwide online survey among adults residing in the United States
Working with economically vulnerable women engaged in sex work: Collaborating with community stakeholders in Southern Uganda
AbstractNabunya, P., Kiyingi, J., Witte, S. S., Sensoy Bahar, O., Jennings Mayo-Wilson, L., Tozan, Y., Nabayinda, J., Mwebembezi, A., Tumwesige, W., Mukasa, B., Namirembe, R., Kagaayi, J., Nakigudde, J., McKay, M. M., & Ssewamala, F. M. (n.d.).Publication year
2022Journal title
Global Public HealthVolume
17Issue
7Page(s)
1215-1231AbstractEconomically vulnerable women engaged in sex work (WESW) comprise one of the key populations with higher prevalence of HIV globally. In Uganda, HIV prevalence among WESW is estimated at 37% and accounts for 18% of all new infections in the country. This paper describes the strategies by which we have engaged community stakeholders in a randomised clinical trial aimed at evaluating the efficacy of adding economic empowerment components to traditional HIV risk reduction to reduce the incidence of STIs and HIV among WESW in Uganda. We demonstrate that stakeholder engagement, including the engagement of WESW themselves, plays a critical role in the adaptation, implementation, uptake, and potential sustainability of evidence-based interventions. To our knowledge, this is the first study to utilise stakeholder engagement involving WESW in Uganda. Researchers working with hard-to-reach populations, such as WESW, are encouraged to invest time and resources to engage key stakeholders through a full range of collaborative activities; and ensure that research is culturally appropriate and meets the needs of all stakeholders involved. Clinical trial registration: ClinicalTrials.gov identifier: NCT03583541.A systematic review of the evidence on the effectiveness and cost-effectiveness of mass screen-and-treat interventions for Malaria control
AbstractKim, S., Luande, V. N., Rocklov, J., Carlton, J. M., & Tozan, Y. (n.d.).Publication year
2021Journal title
American Journal of Tropical Medicine and HygieneVolume
105Issue
6Page(s)
1722-1731AbstractMalaria elimination and eradication efforts have stalled globally. Further, asymptomatic infections as silent transmission reservoirs are considered a major challenge to malaria elimination efforts. There is increased interest in a mass screen-and-treat (MSAT) strategy as an alternative to mass drug administration to reduce malaria burden and transmission in endemic settings. This study systematically synthesized the existing evidence on MSAT, from both epidemiological and economic perspectives. Searches were conducted on six databases (PubMed, EMBASE, CINALH, Web of Science, Global Health, and Google Scholar) between October and December 2020. Only experimental and quasi-experimental studies assessing the effectiveness and/or cost-effectiveness of MSAT in reducing malaria prevalence or incidence were included. Of the 2,424 citation hits, 14 studies based on 11 intervention trials were eligible. Eight trials were conducted in sub-Saharan Africa and three trials in Asia. While five trials targeted the community as a whole, pregnant women were targeted in five trials, and school children in one trial. Transmission setting, frequency, and timing of MSAT rounds, and measured outcomes varied across studies. The pooled effect size of MSAT in reducing malaria incidence and prevalence was marginal and statistically nonsignificant. Only one study conducted an economic evaluation of the intervention and found it to be cost-effective when compared with the standard of care of no MSAT. We concluded that the evidence for implementing MSAT as part of a routine malaria control program is growing but limited. More research is necessary on its short- and longer-term impacts on clinical malaria and malaria transmission and its economic value.Food insecurity among households with children during the COVID-19 pandemic: results from a study among social media users across the United States
AbstractParekh, N., Ali, S. H., O’Connor, J., Tozan, Y., Jones, A. M., Capasso, A., Foreman, J., & DiClemente, R. J. (n.d.).Publication year
2021Journal title
Nutrition JournalVolume
20Issue
1AbstractBackground: In the United States, approximately 11% of households were food insecure prior to the COVID-19 pandemic. The present study aims to describe the prevalence of food insecurity among adults and households with children living in the United States during the pandemic. Methods: This study utilized social media as a recruitment platform to administer an original online survey on demographics and COVID-related food insecurity. The survey was disseminated through an advertisement campaign on Facebook and affiliated platforms. Food insecurity was assessed with a validated six-item United States Department of Agriculture (USDA) Household Food Security Survey Module, which was used to create a six-point numerical food security score, where a higher score indicates lower food security. Individual-level participant demographic information was also collected. Logistic regressions (low/very-low compared with high/marginal food security) were performed to generate adjusted odds ratios (AOR) and 95%CIs for food insecurity and select demographic characteristics. Results: Advertisements reached 250,701 individuals and resulted in 5,606 complete surveys. Overall, 14.7% of participants self-identified as having low or very low food security in their households, with higher prevalence (17.5%) among households with children. Unemployment (AOR:1.76, 95%CI:1.09–2.80), high school or lower education (AOR:2.25, 95%CI:1.29–3.90), and low income (AOR[$30,000-$50,000]:5.87, 95%CI:3.35–10.37; AOR[< $30,000]:10.61, 95%CI:5.50–20.80) were associated with higher odds of food insecurity in multivariable models among households with children (and the whole sample). Conclusions: These data indicate exacerbation of food insecurity during the pandemic. The study will be instrumental in guiding additional research and time-sensitive interventions targeted towards vulnerable food insecure subgroups.Household and hospitalization costs of pediatric dengue illness in Colombo, Sri Lanka
AbstractFernando, E. S., Headley, T. Y., Tissera, H., Wilder-Smith, A., De Silva, A., & Tozan, Y. (n.d.).Publication year
2021Journal title
American Journal of Tropical Medicine and HygieneVolume
105Issue
1Page(s)
110-116AbstractDengue, a mosquito-borne viral infection that affects millions around the world, poses a substantial economic burden in endemic countries. We conducted a prospective costing study in hospitalized pediatric dengue patients at the Lady Ridgeway Hospital for Children (LRHC), a public pediatric hospital in Colombo district, Sri Lanka, to assess household out-of-pocket and hospitalization costs of dengue in pediatric patients during peak dengue transmission season. Between August and October 2013, we recruited 216 hospitalized patients (aged 0-3 years, 27%; 4-7 years, 29%; 8-12 years, 42%) who were clinically or laboratory diagnosed with dengue. Using 2013 US dollars, household out-of-pocket spending, on average, was US$59 (SD 49) per episode and increased with disease severity (DF, US$52; DHF/ DSS, US$78). Pediatric dengue patients received free-of-charge medical care during hospitalization at LRHC, and this places a high financial burden on hospitals. The direct medical cost of hospitalization was US$68 (SD 31.4) for DF episode, and US$122.7 (SD 65.2) for DHF/DSS episode. Yet a hospitalized dengue illness episode still accounted for 20% to 35% of household monthly income due to direct and indirect costs. Additionally, a majority of caregivers (70%) sought outpatient care before hospitalization, most of whom (81%) visited private health facilities. Our findings indicate that hospitalized pediatric dengue illness poses a nontrivial cost burden to households and healthcare systems, emphasizing the importance of preventing and controlling the transmission of dengue in endemic countries.Impact of COVID-19-related knowledge on protective behaviors: The moderating role of primary sources of information
Increased alcohol use during the COVID-19 pandemic: The effect of mental health and age in a cross-sectional sample of social media users in the U.S.
AbstractCapasso, A., Jones, A. M., Ali, S. H., Foreman, J., Tozan, Y., & DiClemente, R. J. (n.d.).Publication year
2021Journal title
Preventive MedicineVolume
145AbstractThe COVID-19 pandemic has triggered a public health crisis of unprecedented scale. Increased alcohol use has been extensively documented during other crises, particularly among persons with anxiety and depression. Despite COVID-19's differential impact by age, the association of age, mental health and alcohol use during the pandemic has not been explored. This study aimed to examine whether age modified the association of anxiety and depressive symptoms with alcohol use during the COVID-19 pandemic. Two online surveys were administered to U.S. adult social media users in March and April 2020. Generalized linear models were conducted in 2020 among 5850 respondents (52.9% female; 22.0% aged 18–39 years, 47.0% aged 40–59 years, and 31.0% aged ≥60 years) to examine if age modified the association of anxiety and depression symptomatology and alcohol use. Overall, 29% of respondents reported increased alcohol use. Adjusted odds ratios of reporting increased alcohol use were 1.41 (95% CI = 1.20–1.66) among respondents with anxiety symptoms and 1.64 (95% CI = 1.21–2.23) among those with depressive symptoms compared to those without such symptoms. Whereas respondents aged 18–39 years had the highest probability of reporting increased alcohol use, the probability of older persons (40–59 and ≥60 years) reporting increased drinking was much greater among those with symptoms of anxiety and depression, compared to those without symptoms. These findings warrant age-differentiated public health messaging on the risks of excessive alcohol use and scale-up of substance use services for middle-aged and older adults with symptoms of depression and anxiety.