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Public Health Sciences

Center for Public Health Modeling and Response

Conceptual framework of Center. Dynamic modeling framework (top) will be used to detect disease hotspots, predict which communities are at highest risk, and develop a resource allocation toolkit (middle) in order to direct field level interventions and other essential resources to communities of greatest need (bottom)

The Center for Public Health Modeling and Response aims to utilize data-driven approaches to inform clinical and public health decision-making and assist the ability of health organizations and communities to prepare for, and respond to, public health threats.

  • Overview

    Our purpose is to improve health outcomes for communities across South Carolina by creating usable knowledge for public health decision makers. Through a dedication to education, research, and service, we aim to train the next generation of public health modelers to develop and implement data-driven approaches to inform and assist clinicians, health organizations, and communities on public health response.   

    There is a public health need to utilize data-driven approaches to inform patient care and community needs. Modeling frameworks are being designed and implemented to help healthcare professionals, patients, and public health implementors with decisions about diagnostic testing, treatment initiation, lifestyle changes, and resource allocation. Such models are especially useful because they can provide objective data on the decision-making process and help avoid biases observed in clinical and public health decision making.

    Our vision is to be a leading resource for usable knowledge for public health decisions makers.

  • Our People

    Director and Staff

    Dr. Lior RennertDr. Lior Rennert, Director
    Dr. Lior Rennert is an Assistant Professor of Biostatistics in the Department of Public Health Sciences at Clemson University. He received his PhD degree in Biostatistics from the University of Pennsylvania’s Pearlman School of Medicine and his MS degree in Statistics from the University of Chicago. His work focuses on the development and application of statistical and mathematical models to guide health-related decision making in the health sciences. Currently, Dr. Rennert and his team are developing an epidemiological modeling framework to identify communities at high-risk for opioid-use disorder, hepatitis C virus (HCV), human immunodeficiency virus (HIV), and respiratory infectious diseases, including Covid-19. The ultimate goal of this project is to develop a toolkit to help inform decision making for resource allocation to medically underserved and at-risk communities. As Clemson University’s Lead Public Health Strategist for Covid-19, Dr. Rennert and his team have developed models that helped guide university policy throughout the Covid-19 pandemic. He also works closely with Prisma Health’s Opioid Stewardship Program to evaluate opioid-related policies on patient well-being. Dr. Rennert has formed partnerships with several organizations statewide, including Prisma Health, Clemson Rural Health, The University of South Carolina’s Center for Rural and Primary Health Care, the Medical University of South Carolina, and South Carolina’s Department of Health and Environmental Control.

    Dr. Kerry HowardDr. Kerry Howard, Research Manager
    Dr. Kerry Howard is the Research Manager at the Center for Public Health Modeling and Response. She received her PhD degree from Clemson University in Applied Health Research and Evaluation and a MS degree from Seton Hall University in Experimental Psychology and Cognitive Neuroscience. Her research focuses on the elimination of health disparities through data-driven examinations of delivery of care in disadvantaged populations, as well as methodology that impacts decision-making in the prevention and treatment of cognitive decline and Alzheimer’s Disease, opioid use disorder, Hepatitis C, and community child safety. Dr. Howard has performed research in the fields of health and psychology over the course of her career, accumulating extensive experience with research design, data maintenance and analysis, and scientific writing, as well as an understanding of how these areas can be applied to improve real-world outcomes and disseminate findings to the community.

    Dr. Fatih GezerDr. Fatih Gezer, Postdoctoral Fellow
    Dr. Fatih Gezer is a Postdoctoral Fellow in the Department of Public Health Sciences at Clemson University. He received his PhD and his Master of Science degrees in Statistics from the University of Leeds in the United Kingdom and the University of Delaware, respectively. He has expertise in Spatio-temporal statistics, spatial point processes, the statistical properties of the geometric structures obtained from points such as Voronoi tessellations, and denoising methods for noisy spatial data. His current research focuses on the application of statistical methods to public health through the mathematical modeling of infectious diseases. 

    Advisory Faculty

    Dr. Ron GimbelDr. Ron Gimbel, Director of Clemson Rural Health, Professor
    Dr. Ronald Gimbel is a Professor in the Department of Public Health Sciences at Clemson University and Director of Clemson Rural Health. He received his PhD from the State University of New York at Albany in Public Administration and Policy and a Master of Arts degree from Webster University in Management. The Clemson Rural Health organization operates rural health clinics, a fleet of mobile health units, telehealth services, and other technologies to enhance overall wellness in South Carolina communities. Dr. Gimbel’s research focuses on improving health equity and outcomes in rural and underserved communities within an effort to bridge biomedical research with communities.

    Dr. Sarah GriffinDr. Sarah Griffin, Interim Department Chair, Professor
    Dr. Sarah Griffin is a Professor and the Interim Department Chair in the Department of Public Health Sciences at Clemson University. She received her PhD in Public Health and a Master of Public Health in Health Promotion, Education, and Behavior degrees from the University of South Carolina. She is a health researcher with extensive community-based research experience and expertise in implementation research. Dr. Griffin's research is focused on eliminating health disparities by researching the efficacy and effectiveness of complex interventions to improve health. She often uses mixed-method approaches to assess the effectiveness of community, clinical, and school based interventions addressing health equity in South Carolina. Currently, Dr. Griffin serves as Co-PI for a Centers for Disease Control and Prevention obesity prevention initiative with rural health extension.

    Dr. Alain LitwinDr. Alain Litwin, Professor
    Dr. Alain Litwin is a Professor of Medicine at the University of South Carolina School of Medicine Greenville, a Professor at Clemson University School of Health Research, executive director of the Addiction Medicine Center at Prisma Health, and co-chair of the Prisma Health Opioid Stewardship Council. He received his MD from Tulane University School of Medicine and specializes in internal and addiction medicine. His research is focused on developing and studying models of Hepatitis C care for drug users and advocating for increasing access to effective care for patients. Through his roles, Dr. Litwin has helped shape public policy through collaboration with community and government organizations to develop clinical guidelines and expand access to treatments.

    Dr. Gary MachlisDr. Gary Machlis, Professor
    Dr. Gary Machlis is a Professor of Environmental Sustainability in the Department of Parks, Recreation and Tourism Management at Clemson University. He received his PhD from Yale University in Human Ecology and his MS from the University of Washington in Forestry. His research interests are disaster response, science during crisis, conservation science and politics, and sustainability. Dr. Machlis has lent his expertise to multiple roles serving communities during crises, including Science Advisor to the Director of the U.S. National Park Service, co-Leader of the U.S. Department of the Interior’s Strategic Sciences Group, and an executive councilman of the National Academics of Sciences, Engineering, and Medicine Response and Resilient Recovery Strategic Science Initiative. He has created an international presence, conducting research and promoting science capacity in China, the Galapagos Islands, Haiti, Kenya, and Eastern Europe.

    Affiliated Faculty

    Dr. Kathleen CartmellDr. Kathleen Cartmell, Associate Professor
    Dr. Kathleen Cartmell is an Associate Professor in the Department of Public Health Sciences at Clemson University. She received her PhD from the Medical University of South Carolina in Health and Rehabilitation Sciences and a Master of Public Health degree from the Emory University Rollins School of Public Health. She is a health services researcher with a focus on dissemination and implementation of evidence-based strategies for disease prevention and control, including interventions to optimize vaccination at the health system and community levels. She now leads a statewide multi-level intervention designed to increase HPV vaccination in South Carolina.

    Dr. Delphine DeanDr. Delphine Dean, Professor
    Dr. Delphine Dean is a Ron and Jane Lindsay Family Innovation Professor in the Department of Bioengineering at Clemson University. She received her PhD and Master of Engineering degrees from the Massachusetts Institute of Technology in Electrical Engineering and Computer Science. She is the director and founder of the Clemson Center for Innovative Medical Devices and Sensors and the Research Education in Disease Diagnosis and Intervention (REDDI) Lab, which includes Clemson's only CLIA certified diagnostic laboratory, and is key in surveillance of COVID-19. She recently served as Project Lead for an NIH award aimed at sequencing all the positive samples from the REDDI Lab for surveillance of emerging strains. 

    Dr. David FreedmanDr. David Freedman, Department Chair, Professor
    David L.  Freedman is a professor in the Department of Environmental Engineering and Earth Sciences at Clemson University; he also serves as the Department Chair.  He received his Ph.D. in Environmental Engineering from Cornell University. Dr. Freedman has received research support from SERDP, ESTCP, EPA, US DOE, US Army Construction Engineering Research Laboratory, US Air Force Office of Scientific Research, Westinghouse Savannah River Corporation, Battelle, and numerous consulting firms.  The main focus of Dr. Freedman’s research is biotic and abiotic degradation of groundwater contaminants.  He also has teaching and research experience with wastewater treatment systems.  During the COVID pandemic, Dr. Freedman led a team that collected data on the prevalence of SARS-CoV-2 in wastewater from three sewer sheds in the Clemson area.  The surveillance data was used to develop an SEIR model that predicts the numbers of infected individuals.  Similar studies are envisioned for other public health issues that can be monitored using wastewater, including the prevalence of opioids. 

    Dr. Natasha MalminDr. Natasha Malmin, Assistant Professor
    Dr. Natasha Malmin is a policy scientist who studies access and procedural equity issues in health and disaster recovery systems. Areas of specialization include public health emergency response, school recovery after disasters, administrative burden and federal disaster recovery, participatory geographic information systems mapping, and community resilience. She has articles appearing in the Journal of Emergency Management, Disaster Medicine and Public Health, Natural Hazards, Natural Hazards Review,Environmental Health, and Applied Geography.

    Dr. Rachel MayoDr. Rachel Mayo, Associate Dean for Research and Graduate Studies, Professor
    Dr. Rachel Mayo is a Professor in the Department of Public Health Sciences and an Associate Dean for Research and Graduate Studies in the College of Behavioral, Social and Health Sciences at Clemson University. Her recent research focuses on delivery of care to Latino patients, experiences with cancer among African Americans, and promotion of participation in breast and cervical cancer screenings among minority populations. Dr. Mayo’s research and evaluation of treatment for newborns with Neonatal Abstinence Syndrome has transformed healthcare research in communities across South Carolina. Her participation on state and national boards, such as the Alliance for a Healthier South Carolina’s Health Disparities Task Force, and Academy Health’s Health Disparities Interest group, have led to a shaping of community and public policy.

    Dr. Christopher McMahanDr. Christopher McMahan, Associate Professor, Associate Director for Graduate Studies
    Dr. Christopher McMahan is an Associate Professor and the Associate Director for Graduate Studies in the School of Mathematical and Statistical Sciences at Clemson University. He received his PhD from the University of South Carolina in Statistics and a Master of Science degree from Western Kentucky University in Mathematics. Dr. McMahan has extensive expertise in machine learning and artificial intelligence applications, COVID-19 modeling, and disease mapping and forecasting. During the 2020-2021 academic year, Dr. McMahan was a member of the public health strategy team which provided public health guidance to Clemson University amid the COVID-19 pandemic. In 2022, Dr. McMahan was named an American Statistical Association Fellow, one of the highest honors for statisticians, due to his exceptional contributions to statistical science, collaboration with researchers internationally, and promotion of scientific discovery across disciplines.

    Graduate Assistants

    Iromi JayawardenaIromi Jayawardena, Graduate Research Assistant
    Iromi Jayawardena is a Graduate Research Assistant in the Department of Public Health Sciences at Clemson University. She received her Master of Science degree from Sam Houston State University in Statistics and is currently a PhD student in the Applied Health Research and Evaluation program at Clemson University. Her primary research projects focus on COVID-19 vaccination and the use of data-driven approaches for vaccination uptake in communities in South Carolina through mobile health clinics.

    Abass BabatundeAbass Babatunde, Graduate Research Assistant
    Abass Babatunde is a Graduate Research Assistant in the Department of Public Health Sciences at Clemson University. He is currently a PhD student in the Applied Health Research and Evaluation program at Clemson University. His research interests include use of public health data to evaluate and guide health intervention to ensure the optimum use of resources, especially in preventing and mitigating poor health outcomes while maintaining equity in access to care and treatment. He has worked in many capacities with international non-governmental agencies and research institutes in community health intervention design, evaluation, and management.

    Bonnie TreadoBonnie Treado, Graduate Research Assistant
    Dr. Bonnie Treado is a Graduate Research Assistant in the Department of Public Health Sciences at Clemson University and with Clemson Rural Health and a board-certified AANP family nurse practitioner. She is currently a PhD student in the Applied Health Research and Evaluation program at Clemson University. She received her DNP and a Master’s degree in Nursing from the Medical University of South Carolina. Dr. Treado has expanded her clinical experience with patients with HIV/AIDs, immigrant communities, and rural populations of South Carolina to develop primary research interests in dissemination and implementation strategies to reduce health disparities in marginalized populations, to optimize health-related communication, and to build capacity within health systems to address community needs.


    Dr. Kerry Sease

    Dr. Zichen Ma

  • Projects

    Data-driven approach to identify high-risk rural communities for delivery of mobile health clinics
    Our team is developing and implementing a modeling framework to identify communities at greatest risk of OUD, hepatitis C virus (HCV), and human deficiency virus (HIV) for delivery of mobile health clinics. We are working with South Carolina’s Center for Rural and Primary Health Care, Clemson Rural Health, and Prisma Health to identify high-risk rural communities for targeted delivery of Mobile Health Clinics.

    Evaluation of policies limiting opioid exposure
    In a joint collaboration between Prisma Health’s Opioid Stewardship Program and Clemson University, our teams are continuously evaluating the immediate impact and downstream effects of policies limiting opioid exposure. Importantly, we have found that policies implemented by Prisma Health, and the State of South Carolina, have successfully limited opioid exposure without compromising patient pain and discomfort.

    Statewide infectious disease surveillance, prediction, and resource allocation
    Our team is working on developing a dynamic simulation modeling framework for surveillance, prediction, and real-time allocation of essential resources to underserved communities in order to reduce health disparities during Covid-19 and future pandemics. Our flexible modeling framework will integrate real-time data on infectious disease outcomes with individual and community level contextual factors to inform infectious disease surveillance and improve understanding of disease epidemiology in underserved communities, and to support the decision-making process for resource allocation to high-risk populations. The proposed modeling toolkit will help inform and assist the distribution of Covid-19 mobile health clinics to medically underserved and at-risk communities.

    Infectious disease Epidemiology
    Understanding infectious disease epidemiology is critical for understanding individual and community risk, conducting accurate disease surveillance, and implementing effective mitigation measures. This knowledge is especially useful to estimate input parameters of modeling frameworks used to allocate resources to at-risk communities. Using statistical models, we have estimated a wide range of Covid-19 epidemiological metrics, including risk of reinfection, vaccine effectiveness and waning immunity, and predictive value of clinical symptoms.

    Covid-19 Modeling for Institutes of Higher Education
    Our team is developing an integrative modeling toolkit for Covid-19 surveillance, prediction, resource allocation, and intervention evaluation in institutes of Higher Education. Our goal is to generalize this toolkit in other institutional settings in order to inform public health decision making. This toolkit has been utilized at Clemson University to inform decision making on a wide variety of mitigation measures (e.g., testing strategies) and procurement of essential resources.    

    Utilizing wastewater surveillance for early disease detection and response
    Utilizing samples collected through wastewater, our team has developed dynamic models to predict active Covid-19 cases in local communities. Currently, we are working to expand wastewater detection to detect communities at high-risk for opioid overdose. The ultimate goal of this project is to supplement resource allocation models with this information to increase the timeliness and effectiveness of mobile health clinic response, community response, and educational efforts.

    Building a campus-community partnership to raise public health awareness
    With funding from the Interfaith Youth Core and FIVA Carolinas, we have built a partnership with 60 African-American churches in order to raise Covid-19 vaccine awareness and distribute other Covid-related information.

    Identifying predictors of cognitive decline in older adults
    Our team is working on an extensive examination of the relationship between cognitive reserve built up through life experiences and cognitive decline in older adults. The ultimate goal is to help identify influential factors of cognitive decline and potential timing for early interventions to promote cognitive health in older adults.

  • Research Publications

    Rennert L, Ma Z, McMahan CS, Dean D. Covid-19 vaccine effectiveness against general SARS-CoV-2 infection from the omicron variant: A retrospective cohort study. Katoto PD, editor. PLOS Glob Public Health. 2023;3(1):e0001111.

    Rennert L, Howard KA, Walker KB, Furmanek DL, Blackhurst DW, Cancellaro VA, Litwin AH. Evaluation of policies limiting opioid exposure on opioid prescribing and patient pain in opioid-naive patients undergoing elective surgery in a large American health system. J Patient Saf. 2022.

    Rennert L, Ma Z, McMahan CS, Dean D. Effectiveness and protection duration of Covid-19 vaccines and previous infection against any SARS-CoV-2 infection in young adults. Nat Commun. 2022;13(1):3946.

    McMahan CS, Lewis D, Deaver JA, Dean D, Rennert L, Kalbaugh CA, Shi L, Kriebel D, Graves, D, Popat SC, Karanfil T, Freedman DL. Predicting COVID-19 infected individuals in a defined population from wastewater RNA data. ACS EST Water. 2022;2(11):2225–32.

    Kunkel D, Stuenkel M, Sivaraj LB, Colenda CC, Pekarek L, Rennert L. Predictive value of clinical symptoms for COVID-19 diagnosis in young adults. J Am Coll Health. 2022;1–4.

    King KL, Wilson S, Napolitano JM, Sell KJ, Rennert L, Parkinson CL, Dean D. SARS-CoV-2 variants of concern Alpha and Delta show increased viral load in saliva. Abd El-Aty AM, editor. PLOS ONE. 2022;17(5):e0267750.

    Pericot-Valverde I, Heo M, Niu J, Rennert L, Norton BL, Akiyama MJ, Arsten J, Litwin AH. Relationship between depressive symptoms and adherence to direct-acting antivirals: Implications for Hepatitis C treatment among people who inject drugs on medications for opioid use disorder. Drug Alcohol Depend. 2022;234:109403.

    Rennert L, McMahan CS. Risk of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) reinfection in a university student population. Clin Infect Dis. 2022;74(4):719–22.

    Plumb EV, Ham RE, Napolitano JM, King KL, Swann TJ, Kalbaugh CA, Rennert L, Dean D. Implementation of a rural community diagnostic testing strategy for SARS-CoV-2 in Upstate South Carolina. Front Public Health. 2022;10:858421.

    Gormley MA, Akiyama MJ, Rennert L, Howard KA, Norton BL, Pericot-Valverde I, Muench S, Heo M, Litwin AH. Changes in health-related quality of life for Hepatitis C Virus–infected people who inject drugs while on opioid agonist treatment following sustained virologic response. Clin Infect Dis. 2022;74(9):1586–93.

    McMahan CS, Self S, Rennert L, Kalbaugh C, Kriebel D, Graves D, Colby C, Deaver JA, Popal SC, Karanfil T, Freedman DL. COVID-19 wastewater epidemiology: A model to estimate infected populations. Lancet Planet Health. 2021;5(12):e874–81.

    Rennert L, Kalbaugh CA, McMahan CS, Shi L, Colenda CC. The impact of phased university reopenings on mitigating the spread of COVID-19: A modeling study. BMC Public Health. 2021;21(1):1520.

    Massimo L, Rennert L, Xie SX, Olm C, Bove J, Van Deerlin V, Irwin DJ, Grossman M, McMillan CT. Common genetic variation is associated with longitudinal decline and network features in behavioral variant frontotemporal degeneration. Neurobiol Aging. 2021;108:16–23.

    Howard KA, Rennert L, Pericot-Valverde I, Heo M, Norton BL, Akiyama MJ, Agyemang L, Litwin AH. Utilizing patient perception of group treatment in exploring medication adherence, social support, and quality of life outcomes in people who inject drugs with Hepatitis C. J Subst Abuse Treat. 2021;126:108459.

    Rennert L, McMahan CS, Kalbaugh CA, Yang Y, Lumsden B, Dean D, Pekarek L, Colenda CC. Surveillance-based informative testing for detection and containment of SARS-CoV-2 outbreaks on a public university campus: An observational and modelling study. Lancet Child Adolesc Health. 2021;5(6):428–36.

    Heo M, Pericot-Valverde I, Rennert L, Akiyama MJ, Norton BL, Gormley M, Agyemand L, Arnsten JH, Litwin AH. Hepatitis C Virus direct-acting antiviral treatment adherence patterns and sustained viral response among people who inject drugs treated in opioid agonist therapy programs. Clin Infect Dis. 2021;73(11):2093–100.

    Rennert L, Heo M, Litwin AH, Gruttola VD. Accounting for confounding by time, early intervention adoption, and time-varying effect modification in the design and analysis of stepped-wedge designs: application to a proposed study design to reduce opioid-related mortality. BMC Med Res Methodol. 2021;21(1):53.

    Charron E, Rennert L, Mayo RM, Eichelberger KY, Dickes L, Truong KD. Contraceptive initiation after delivery among women with and without opioid use disorders: A retrospective cohort study in a statewide Medicaid population, 2005–2016. Drug Alcohol Depend. 2021;220:108533.

    Pericot‐Valverde I, Rennert L, Heo M, Akiyama MJ, Norton BL, Agyemang L, Lumsden B, Litwin AH. Rates of perfect self‐reported adherence to direct‐acting antiviral therapy and its correlates among people who inject drugs on medications for opioid use disorder: The PREVAIL study. J Viral Hepat. 2021;28(3):548–57.

    Rennert L, Kalbaugh CA, Shi L, McMahan CS. Modelling the impact of presemester testing on COVID-19 outbreaks in university campuses. BMJ Open. 2020;10(12):e042578.

Department of Public Health Sciences
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