Yesim Tozan

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, Turkey
MS, Environmental Technology, Bogazici University, Turkey
MA, Public Affairs, Princeton University, Princeton, NJ
PhD, Public Affairs, Princeton University, Princeton, NJ

Areas of research and study

Cost Effectiveness
Cost-effective Health Programs and Policies
Economic Evaluation
Health Economics
Infectious Diseases
Prevention Interventions

Publications

Publications

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

Jennings 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

2023

Journal title

Journal of Interpersonal Violence

Volume

38

Issue

1

Page(s)

NP1920-NP1949
Abstract
Abstract
Economic 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.

"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

Sensoy 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

2022

Journal title

BMC Women's Health

Volume

22

Issue

1
Abstract
Abstract
Background: 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

Mutumba, 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

2022

Journal title

JMIR Research Protocols

Volume

11

Issue

10
Abstract
Abstract
Background: 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.

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

Huang, K. Y., Nakigudde, J., Kisakye, E. N., Sentongo, H., Dennis-Tiwary, T. A., Tozan, Y., Park, H., & Brotman, L. M. (n.d.).

Publication year

2022

Journal title

International Journal of Mental Health Systems

Volume

16

Issue

1
Abstract
Abstract
Background: 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

Liyanage, P., Tozan, Y., Tissera, H. A., Overgaard, H. J., & Rocklöv, J. (n.d.).

Publication year

2022

Journal title

Parasites and Vectors

Volume

15

Issue

1
Abstract
Abstract
Background: 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

Liyanage, P., Tozan, Y., Overgaard, H. J., Aravinda Tissera, H., & Rocklöv, J. (n.d.).

Publication year

2022

Journal title

The Lancet Planetary Health

Volume

6

Issue

7

Page(s)

e577-e585
Abstract
Abstract
Background: 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

Capasso, A., Kim, S., Ali, S. H., Jones, A. M., DiClemente, R. J., & Tozan, Y. (n.d.).

Publication year

2022

Journal title

BMC public health

Volume

22

Issue

1
Abstract
Abstract
Background: 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

DiClemente, R. J., Capasso, A., Ali, S. H., Jones, A. M., Foreman, J., & Tozan, Y. (n.d.).

Publication year

2022

Journal title

Zeitschrift fur Gesundheitswissenschaften

Volume

30

Issue

8

Page(s)

2069-2079
Abstract
Abstract
AIM: Given the need for data to inform public health messaging to mitigate the COVID-19 pandemic, this national survey sought to assess the state of COVID-19-related knowledge, beliefs, mental health, substance use changes, and behaviors among a sample of U.S. adults.SUBJECT AND METHODS: In the period March 20-30, 2020, we collected data on COVID-19-related knowledge, awareness and adoption of preventive practices, depression and anxiety (Patient Health Questionnaire-4), stress (Impact of Event Scale-6), pessimism, and tobacco and alcohol use. Differences between age groups (18-39 years, 40-59 years and ≥ 60 years) were tested using Pearson's chi-squared tests or ANOVAs; associations between drinking and smoking and depression, anxiety, and stress were tested using adjusted logistic regression models.RESULTS: Approximately half of the sample ( N Total  = 6391) were 50-69 years old and 58% were female. COVID-19 knowledge (mean = 12.0; SD = 1.2) and protective practice awareness (mean = 9.1; SD = 0.8) were high. Among respondents, 44% had a score consistent with depression and anxiety (PHQ-4 score ≥ 6), and 52% reported high stress scores (≥ median of 1.33). COVID-19-related anxiety and depression were associated with increased drinking (AOR = 1.79; 95% CI = 1.49, 2.15) and smoking (AOR = 2.17; 95% CI = 1.64, 2.88). High stress scores were also associated with increased drinking (AOR = 1.80; 95% CI = 1.49, 2.17, p  < 0.001) and smoking (AOR = 1.75; 95% CI = 1.31, 2.33). CONCLUSIONS: In spite of high knowledge levels, important gaps were identified. High prevalence of poor mental health outcomes and associated increases in drinking and smoking warrant ongoing risk communications tailoring to effectively disseminate information and expanding psychosocial services, particularly via telehealth, to mitigate the negative mental health impact of COVID-19.SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10389-021-01564-4.

PrEP acceptability and initiation among women engaged in sex work in Uganda: Implications for HIV prevention

Witte, 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

2022

Journal title

EClinicalMedicine

Volume

44
Abstract
Abstract
Background: 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

Kiyingi, 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

2022

Journal title

PloS one

Volume

17

Issue

9
Abstract
Abstract
Introduction 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.

Self-Reported Adherence to Antiretroviral Therapy (ART) Among Women Engaged in Commercial Sex Work in Southern Uganda

Kiyingi, 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

2022

Journal title

AIDS and Behavior
Abstract
Abstract
We 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.

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

Kim, S., Headley, T. Y., & Tozan, Y. (n.d.).

Publication year

2022

Journal title

PLoS Medicine

Volume

19

Issue

8
Abstract
Abstract
Background 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

Kim, S., Capasso, A., Ali, S. H., Headley, T., DiClemente, R. J., & Tozan, Y. (n.d.).

Publication year

2022

Journal title

BMC public health

Volume

22

Issue

1
Abstract
Abstract
Background: Tackling infodemics with flooding misinformation is key to managing the COVID-19 pandemic. Yet only a few studies have attempted to understand the characteristics of the people who believe in misinformation. Methods: Data was used from an online survey that was administered in April 2020 to 6518 English-speaking adult participants in the United States. We created binary variables to represent four misinformation categories related to COVID-19: general COVID-19-related, vaccine/anti-vaccine, COVID-19 as an act of bioterrorism, and mode of transmission. Using binary logistic regression and the LASSO regularization, we then identified the important predictors of belief in each type of misinformation. Nested vector bootstrapping approach was used to estimate the standard error of the LASSO coefficients. Results: About 30% of our sample reported believing in at least one type of COVID-19-related misinformation. Belief in one type of misinformation was not strongly associated with belief in other types. We also identified 58 demographic and socioeconomic factors that predicted people’s susceptibility to at least one type of COVID-19 misinformation. Different groups, characterized by distinct sets of predictors, were susceptible to different types of misinformation. There were 25 predictors for general COVID-19 misinformation, 42 for COVID-19 vaccine, 36 for COVID-19 as an act of bioterrorism, and 27 for mode of COVID-transmission. Conclusion: Our findings confirm the existence of groups with unique characteristics that believe in different types of COVID-19 misinformation. Findings are readily applicable by policymakers to inform careful targeting of misinformation mitigation strategies.

Working with economically vulnerable women engaged in sex work: Collaborating with community stakeholders in Southern Uganda

Nabunya, 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

2022

Journal title

Global Public Health

Volume

17

Issue

7

Page(s)

1215-1231
Abstract
Abstract
Economically 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

Kim, S., Luande, V. N., Rocklov, J., Carlton, J. M., & Tozan, Y. (n.d.).

Publication year

2021

Journal title

American Journal of Tropical Medicine and Hygiene

Volume

105

Issue

6

Page(s)

1722-1731
Abstract
Abstract
Malaria 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.

Examining Changes in Sleep Duration Associated with the Onset of the COVID-19 Pandemic: Who is Sleeping and Who is Not?

Batool-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

2021

Journal title

Behavioral Medicine
Abstract
Abstract
The 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.

Food insecurity among households with children during the COVID-19 pandemic: results from a study among social media users across the United States

Parekh, N., Ali, S. H., O’Connor, J., Tozan, Y., Jones, A. M., Capasso, A., Foreman, J., & DiClemente, R. J. (n.d.).

Publication year

2021

Journal title

Nutrition Journal

Volume

20

Issue

1
Abstract
Abstract
Background: 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

Fernando, E. S., Headley, T. Y., Tissera, H., Wilder-Smith, A., De Silva, A., & Tozan, Y. (n.d.).

Publication year

2021

Journal title

American Journal of Tropical Medicine and Hygiene

Volume

105

Issue

1

Page(s)

110-116
Abstract
Abstract
Dengue, 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

Kim, S., Capasso, A., Cook, S. H., Ali, S. H., Jones, A. M., Foreman, J., DiClemente, R. J., & Tozan, Y. (n.d.).

Publication year

2021

Journal title

PloS one

Volume

16

Issue

11
Abstract
Abstract
This study assessed the modifying role of primary source of COVID-19 information in the association between knowledge and protective behaviors related to COVID-19 among adults living in the United States (US). Data was collected from 6,518 US adults through an online cross-sectional self-administered survey via social media platforms in April 2020. Linear regression was performed on COVID-19 knowledge and behavior scores, adjusted for sociodemographic factors. An interaction term between knowledge score and primary information source was included to observe effect modification by primary information source. Higher levels of knowledge were associated with increased self-reported engagement with protective behaviors against COVID-19. The primary information source significantly moderated the association between knowledge and behavior, and analyses of simple slopes revealed significant differences by primary information source. This study shows the important role of COVID-19 information sources in affecting people's engagement in recommended protective behaviors. Governments and health agencies should monitor the use of various information sources to effectively engage the public and translate knowledge into behavior change during an evolving public health crisis like COVID-19.

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.

Capasso, A., Jones, A. M., Ali, S. H., Foreman, J., Tozan, Y., & DiClemente, R. J. (n.d.).

Publication year

2021

Journal title

Preventive Medicine

Volume

145
Abstract
Abstract
The 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.

Predictors of Depressive Symptoms and Post Traumatic Stress Disorder Among Women Engaged in Commercial Sex Work in Southern Uganda

Nabunya, P., Byansi, W., Damulira, C., Bahar, O. S., Jennings Mayo-Wilson, L., Tozan, Y., Kiyingi, J., Nabayinda, J., Braithwaite, R., Witte, S. S., & Ssewamala, F. M. (n.d.).

Publication year

2021

Journal title

Psychiatry Research

Volume

298
Abstract
Abstract
This study examined the factors associated with depressive symptoms and post traumatic depressive disorder (PTSD) among economically vulnerable women engaged in commercial sex work (WESW) in southern Uganda. Baseline data from a longitudinal cluster randomized study involving 542 self-identified WESW (18-55 years), recruited from 19 HIV hotspots were analyzed. Hierarchical linear regression modelling was utilized to estimate individual, family-level and economic-level predictors of depressive symptoms and PTSD. Family cohesion, sex work stigma, HIV status, financial distress, household assets, number of children and number of household income earners, were associated with PTSD. Similarly, family cohesion, number of people in the household, HIV status, sex work stigma, financial distress, and household assets, were associated with depressive symptoms. Women engaged in commercial sex work are at a higher risk of HIV and poor mental health outcomes. Sex work stigma and financial distress elevate levels of depressive symptoms and PTSD, over and above an individual's HIV status. Family and economic-level factors have the potential to mitigate the risk of poor mental health outcomes. As such, integrating stigma reduction and economic strengthening components in the programming targeting WESW—a key population, may be critical to address their mental health outcomes.

Regional and socioeconomic predictors of perceived ability to access coronavirus testing in the United States: results from a nationwide online COVID-19 survey

Ali, S. H., Tozan, Y., Jones, A. M., Foreman, J., Capasso, A., & DiClemente, R. J. (n.d.).

Publication year

2021

Journal title

Annals of Epidemiology

Volume

58

Page(s)

7-14
Abstract
Abstract
Purpose: Access to COVID-19 testing remained a salient issue during the early months of the pandemic, therefore this study aimed to identify 1) regional and 2) socioeconomic predictors of perceived ability to access Coronavirus testing. Methods: An online survey using social media-based advertising was conducted among U.S. adults in April 2020. Participants were asked whether they thought they could acquire a COVID-19 test, along with basic demographic, socioeconomic and geographic information. Results: A total of 6,378 participants provided data on perceived access to COVID-19 testing. In adjusted analyses, we found higher income and possession of health insurance to be associated with perceived ability to access Coronavirus testing. Geographically, perceived access was highest (68%) in East South Central division and lowest (39%) in West North Central. Disparities in health insurance coverage did not directly correspond to disparities in perceived access to COVID-19 testing. Conclusions: Sex, geographic location, income, and insurance status were associated with perceived access to COVID-19 testing; interventions aimed at improving either access or awareness of measures taken to improve access are warranted. These findings from the pandemic's early months shed light on the importance of disaggregating perceived and true access to screening during such crises.

The effectiveness of malaria camps as part of the Durgama Anchalare Malaria Nirakaran (DAMaN) program in Odisha, India: study protocol for a cluster-assigned quasi-experimental study

The efficacy and cost-effectiveness of a family-based economic empowerment intervention (Suubi + Adherence) on suppression of HIV viral loads among adolescents living with HIV: results from a Cluster Randomized Controlled Trial in southern Uganda

Tozan, Y., Capasso, A., Sun, S., Neilands, T. B., Damulira, C., Namuwonge, F., Nakigozi, G., Mwebembezi, A., Mukasa, B., Sensoy Bahar, O., Nabunya, P., Mellins, C. A., McKay, M. M., & Ssewamala, F. M. (n.d.).

Publication year

2021

Journal title

Journal of the International AIDS Society

Volume

24

Issue

6
Abstract
Abstract
Introduction: Evidence from low-resource settings indicates that economic insecurity is a major barrier to HIV treatment adherence. Economic empowerment (EE) interventions have the potential to improve adherence outcomes among adolescents living with HIV (ALWHIV) by mitigating the effects of poverty. This study aims to assess the efficacy and cost-effectiveness of a savings-led family-based EE intervention, Suubi + Adherence, aimed at improving antiretroviral therapy (ART) adherence outcomes ALWHIV in Uganda. Methods: Adolescents (mean age 12 years at enrolment; 56% female) receiving ART for HIV at 39 health centres were randomized to Suubi + Adherence intervention (n = 358) or bolstered standard of care (BSOC; n = 344). A difference-in-differences analysis was employed to assess the change in the proportion of virally suppressed adolescents (HIV RNA viral load <40 copies/mL) over 24 months. The cost-effectiveness analysis examined how much the intervention cost to virally suppress one additional adolescent relative to BSOC from the healthcare provider perspective. Results: At 24 months, the intervention was associated with an 8.85-percentage point [95% confidence interval (CI) 0.80 to 16.90 percentage points] increase in the proportion of virally suppressed adolescents between the study arms (p = 0.032). Per-participant costs were US$177 and US$263 for the BSOC and intervention groups respectively. The incremental cost of virally suppressing one additional adolescent was estimated at US$970 [95% CI, US$508 to 10,725] over two years. Conclusions: Our results support the integration of family-based EE interventions into adherence-support strategies as part of routine HIV care in low-resource settings to address the underlying economic drivers of poor ART adherence among ALWHIV. Moreover, per-participant costs to achieve viral suppression do not seem prohibitive compared to other community-based adherence interventions targeted at ALWHIV in low-resource settings. Further research on combination interventions at the nexus of economic security and HIV treatment and care is needed to inform the development of feasible and scalable HIV policies and programmes.

Reviewing estimates of the basic reproduction number for dengue, Zika and chikungunya across global climate zones

Liu, Y., Lillepold, K., Semenza, J. C., Tozan, Y., Quam, M. B., & Rocklöv, J. (n.d.).

Publication year

2020

Journal title

Environmental Research

Volume

182
Abstract
Abstract
Background: Globally, dengue, Zika virus, and chikungunya are important viral mosquito-borne diseases that infect millions of people annually. Their geographic range includes not only tropical areas but also sub-tropical and temperate zones such as Japan and Italy. The relative severity of these arboviral disease outbreaks can vary depending on the setting. In this study we explore variation in the epidemiologic potential of outbreaks amongst these climatic zones and arboviruses in order to elucidate potential reasons behind such differences. Methodology: We reviewed the peer-reviewed literature (PubMed) to obtain basic reproduction number (R0) estimates for dengue, Zika virus, and chikungunya from tropical, sub-tropical and temperate regions. We also computed R0 estimates for temperate and sub-tropical climate zones, based on the outbreak curves in the initial outbreak phase. Lastly we compared these estimates across climate zones, defined by latitude. Results: Of 2115 studies, we reviewed the full text of 128 studies and included 65 studies in our analysis. Our results suggest that the R0 of an arboviral outbreak depends on climate zone, with lower R0 estimates, on average, in temperate zones (R0 = 2.03) compared to tropical (R0 = 3.44) and sub-tropical zones (R0 = 10.29). The variation in R0 was considerable, ranging from 0.16 to 65. The largest R0 was for dengue (65) and was estimated by the Ross-Macdonald model in the tropical zone, whereas the smallest R0 (0.16) was for Zika virus and was estimated statistically from an outbreak curve in the sub-tropical zone. Conclusions: The results indicate climate zone to be an important determinant of the basic reproduction number, R0, for dengue, Zika virus, and chikungunya. The role of other factors as determinants of R0, such as methods, environmental and social conditions, and disease control, should be further investigated. The results suggest that R0 may increase in temperate regions in response to global warming, and highlight the increasing need for strengthening preparedness and control activities.

Contact

tozan@nyu.edu 708 Broadway 4FL New York, NY, 10003