What is Applied Epidemiology?

Epidemiology is defined by John Last from A Dictionary of Epidemiology as “the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.” Applied epidemiology is a branch of epidemiology that utilizes the findings from epidemiologic studies to (1) define and track disease for informed decisions, (2) develop effective interventions, (3) evaluate public health services and health care, (4) communicate data to health professionals, stakeholders, and the public, and (5) emphasize epidemiologic methods for creating health policy. A majority of Applied Epidemiologists work for governmental agencies, such as local and state health departments, and most have a Master of Public Health (MPH) or similar degrees.4 Over 16,000 MPH degrees are awarded annually but only 8% of those who work in the governmental public health workforce hold one.5 Compared to general epidemiology, applied epidemiology focuses on the development of policy and health reform from epidemiologic findings and surveillance. Applied epidemiology data is used to inform resource allocation to promote population health initiatives.

Career Paths

Applied epidemiology is a career path specializing in research, statistics, data analysis and community engagement. Applied epidemiologists work in governmental agencies. The job classifications may include epidemiologists, researchers, data analysts, scientists, or project managers. In addition to state, territorial, local, and tribal (STLT) work settings, applied epidemiology can be used in positions at global health agencies, nonprofit organizations, academia, hospital/health systems and in the pharmaceutical industry. There are varying tiers of epidemiology careers with differing duties and responsibilities including:

Tier 1: Entry-Level Epidemiologist:

  • Participate in epidemiologic investigations
  • Participate in surveillance activities
  • Consult on scientific and technical issues
  • Present, publicize, and disseminate data and epidemiologic findings
  • Participate in development of community partnerships to support epidemiologic investigations
  • Describe surveillance systems that include groups of special concern (disadvantaged or minority groups, groups subject to health disparities, historically underrepresented groups)
  • Use skills that foster collaborations, strong partnerships, and team building
  • Prepare for emergency response

Tier 2: Mid-Level Epidemiologist:

  • Conduct epidemiologic investigations
  • Participate in surveillance activities
  • Epidemiologic consultation on scientific and technical issues provision
  • Develop and disseminate data and epidemiologic findings
  • Design surveillance systems to include groups of special concern (disadvantaged or minority groups, groups subject to health disparities, historically underrepresented groups)
  • Use laboratory resources to support epidemiologic activities
  • Assist in developing a budget that will support organizational epidemiologic activities
  • Assist in preparation of proposals for external funding
  • Use performance measures to evaluate and improve epidemiology program effectiveness

Tier 3a: Senior-Level Epidemiologist, Supervisor or Manager:

  • Supervise and manage
  • Investigate epidemiologic studies and urgent outbreak investigations
  • Disseminate program data, information, and findings
  • Determine evidence-based interventions and control measures in response to epidemiologic findings
  • Ensure evaluation of programs
  • Lead epidemiologic studies, public health programs, and community public health planning processes at the state, local, or tribal level
  • Ensure study design and data collection, dissemination, and use of ethical/legal principles
  • Use knowledge of specific sociocultural factors in the population to interpret findings
  • Ensure that actions are relevant to the affected community
  • Create operational and financial plans for future epidemiologic activities
  • Promote the epidemiologic perspective in the agency strategic planning process
  • Use performance measures to evaluate and improve epidemiology program effectiveness
  • Ensure professional development of epidemiology workforce

Tier 3b: Senior Scientist/Subject Area Expert:

  • Lead scientific teams
  • Conduct epidemiologic investigations
  • Disseminate program data, information and findings
  • Epidemiologic consultation of scientific and technical issues
  • Design investigation of acute and chronic conditions or other adverse outcomes in the population
  • Synthesize principles of good ethical/legal practice for application to study design and data collection, dissemination, and use
  • Formulate new interventions based on evidence when available, and control measures in response to epidemiologic findings
  • Develop processes for using laboratory resources to support epidemiologic activities
  • Develop and manage information systems to improve effectiveness of surveillance, investigation, and other epidemiologic practices
  • Lead epidemiologic studies, public health programs, and community public health planning processes at the state, local, or tribal level
  • Bring epidemiologic perspective in the development and analysis of public health policies

Each tier adheres to the eight skill domains of applied epidemiology competencies (AECs). Tier 1, 2, 3a, and 3b learn, demonstrate, and attain the eight domains as appropriate to their position. These domains include:

  1. Assessment and Analysis
  2. Basic Public Health Science
  3. Communication
  4. Community Dimensions of Practice
  5. Cultural Competency
  6. Financial and Operational Planning and Management (Operational Planning, Financial Planning, and Management Skills)
  7. Leadership and Systems Thinking
  8. Policy Development

Job Outlook and Training

The demand for epidemiologists is increasing, especially in local and state health departments.6 For the general field of epidemiology, the projected increase in employment is 5% or around 400 epidemiologists between 2018-2028.4* CSTE regularly enumerates and describes the applied epidemiology workforce through the Epidemiology Capacity Assessment (ECA). In 2021, the ECA identified 4,135 applied epidemiologists working in state health departments and an additional 2,196 were needed to achieve ideal capacity.Despite the number of public health graduates increasing, the number of those studying epidemiology has remained the same.8 Those leaving the workforce also impact the job outlook. Departures due to retirement and leaving for another job affect the availability of positions.  In 2017, 2.35% of epidemiologists intended to retire within the next year and 24.52% of epidemiologists intended to leave their position in the next year.9

Epidemiologists are highly trained with 88% having a Master’s degree or higher.6 Communication skills, critical thinking skills, detail-orientation and analytical skills are critical to excelling in epidemiology. Epidemiologists often express a desire to create positive and meaningful change in their communities and to improve population health.

*This data was collected prior to the COVID-19 pandemic.

Subject Areas

Applied Epidemiology covers a range of subject areas within public health. Listed below are some subject areas and examples of applied epidemiology practices and tools that contribute to them: 

Surveillance systems

An epidemiologist uses multiple data sources to inform case investigation. The Reportable Condition Knowledge Management System (RCKMS)provides comprehensive information on public health reporting requirements to public health reporters such as clinicians and Epidemiologists can use RCKMS to gather data from one source that has input from multiple parties. RCKMS allows epidemiologists and other public health professionals to provide a mechanism to communicate updates to clinical partners and, improve timeliness, data quality, and completeness of case reports.

Infectious Disease

Applied epidemiologists investigate complaints of foodborne related illness. The Foodborne Disease Outbreak Surveillance System (FDOSS) aides in determining foods associated in outbreaks, germs associated in outbreaks, where germs contaminate food in the production chain, and where the outbreaks happen. FDOSS can be used by epidemiologists to declare and oversee outbreaks, order recalls, and conduct contact tracing. The data collected as part of the epidemiologic investigation can lead to restaurant closures or other control measures to prevent others from becoming ill. The Council for Improving Foodborne Outbreak Response (CIFOR) created The CIFOR Guidelines for Foodborne Disease Outbreak Response for applied epidemiologists contains evidence-based information on foodborne disease investigation for state, local, and federal health agencies. The guidance includes model practices for foodborne disease outbreaks, including preparation, detection, investigation, control, and follow-up as well as roles of key organizations in outbreaks. Applied epidemiologists aim to assess, monitor, and control tuberculosis (TB). Applied epidemiologists contribute to TB outbreak detection, and response by investigating cases of TB, contract tracing, genotype surveillance, and evaluating medical treatment to reduce viral load. Managing risk and exposures amongst at-risk populations, such as homeless persons, injection drug users, persons with HIV, and those who work or reside in facilities or institutions, is another responsibility for epidemiologists. These populations are at a higher risk of contracting TB due to underlying health conditions, lifestyle choices, housing arrangements and occupational exposures. It is important for epidemiologists and public health professionals to incorporate coordinated care for at-risk groups and minimize exposure to others.

Maternal and Child Health

Epidemiologists use public health surveillance and epidemiologic analysis to guide public health practice and improve Maternal Child Health. The Pregnancy Risk Assessment Monitoring System (PRAMS) can be used by epidemiologists and public health professionals to provide expecting mothers lactation counseling, promote early childhood education, and inform policies to reduce maternal mortality. PRAMS is an ongoing, state-specific, population-based surveillance system that helps answer the question of why some babies are born healthy and others are not. In Oklahoma, PRAMS was used to improve infant outcomes by improving the health of women before conception. It was found that only 12% of new mothers received advice or counseling before becoming pregnant.11 After evaluating preconception health indicators from PRAMS, the Preconception/Interception Care and Education Workgroup was formed and has had successful outcomes, such as developing a preconception health tool to identify and educate about risks before pregnancy.11 This health tool is used by family planning clinics, private clinics, tribal health facilities and a nurse home visiting program to improve outcomes.11

Health Disparities

Applied epidemiologists monitor trends in health disparities across health conditions and produce reports of significant findings that influence health policies and interventions. The Practical Playbook aides in building partnerships between primary care and public health groups to improve population health. The Practical Playbook includes real-life, flexible guidance to help the user through each state of partnership building. Playbook manages a National Advisory Committee working to improve collaborations and population health. Collaboration between primary care and public health professionals assists in addressing the larger population health issues rooted in the community. For example, primary care and public health professionals were able to address childhood and adult obesity in Philadelphia through the Healthy Corner Store Initiative. While there were already interventions in place to decrease obesity, research found that junk food purchased from corner stores was contributing significantly to the consumption of excess calories.12 The Food Trust, Philadelphia Department of Health, and Center for Urban Health have worked together to increase healthy food options, offer in-store community nutrition education lessons as well as preventive services, and promote healthy messages and community engagement.12

Disaster Epidemiology

Epidemiologists determine critical health needs and assess the impact of the disaster on the community. The Community Assessment for Public Health Emergency Response (CASPER) is an epidemiologic technique that provides public health leaders with household-based information about a community during an emergency in a timely and accurate way. CASPER can also be used to identify risk factors, distribute resources, track disease trends, determine action items, target interventions and provide information for decision makers. Those called to respond to a disaster and use CASPER are usually interdisciplinary teams that can consist of epidemiologists, health educators, physicians, and community leaders.

CSTE Support

Membership with CSTE provides a community of practice with like-minded, interested colleagues, and lifelong learners across the country. CSTE members use the power of applied epidemiology to improve the public’s health by:

For more information on CSTE membership, visit https://www.cste.org/page/JoinCSTE.


  1. Brownson, R. C., & Petitt, D. B. (2006). Preface. In Brownson, R. C., & Petitti, D.B. (Eds.) Applied epidemiology theory to practice (pp. ix-x). New York, New York: Oxford University Press
  2. Brownson, R. C., Samet, J. M., & Bensyl, D. M. (2017). Applied epidemiology and public health: Are we training the future generations appropriately? Annals of Epidemiology, 27(2), 77-82. doi:10.1016/j.annepidem.2016.12.002
  3. Thacker, S. B., & Buffington, J. (2001). Applied epidemiology for the 21st Century. International Journal of Epidemiology, 30(2), 320-325. doi:10.1093/ije/30.2.320
  4. S. Department of Labor, Bureau of Labor Statistics. (2020) Epidemiologists: Occupational Outlook Handbook. Retrieved from https://www.bls.gov/OOH/life-physical-and-social-science/epidemiologists.htm
  5. Leider, J. P., Sellers, K., Bogaert, K., Castrucci, B. C., Erwin, P. C. (2020) Master’s-Level Education in the Governmental Public Health Workforce. Sage Journals. https://doi.org/10.1177%2F0033354920943519
  6. (2014) 2013 National assessment of epidemiologic capacity: findings and recommendations. Retrieved from http://www.cste2.org/2013eca/CSTEEpidemiologyCapacityAssessment2014-final2.pdf
  7. Council of State and Territorial Epidemiologists. (2021). 2021 Epidemiology Capacity Assessment. Atlanta, Georgia. https://www.cste.org/group/ECA
  8. Leider, J. P., Plepys, C. M., Castrucci, B. C., Burke, E. M., & Blakely, C. H. (2018). Trends in the Conferral of Graduate Public Health Degrees: A Triangulated Approach. Public Health Reports, 133(6), 729-737. doi:10.1177/0033354918791542
  9. Daly, E. (2020). Exploring the Role and Readiness of State Health Department Epidemiologists to work in Emerging Areas of Public Health Practice. Doctoral dissertation, University of North Carolina Chapel Hill. Retrieved from https://cdr.lib.unc.edu/downloads/1g05fj032
  10. Centers for Disease Control and Prevention. (2019). Use of Colorectal Cancer Screen (2018 Behavioral Risk Factor Surveillance System. Retrieved from
  11. Centers for Disease Control and Prevention. (n.d.). Using Oklahoma PRAMS Data to Influence Preconception and Interconception Care. Retrieved from https://www.cdc.gov/prams/state-success-stories/Oklahoma.html
  12. Practical Playbook. (n.d.). Healthy Corner Stores: Philadelphia’s Model for Improving Food Access. Retrieved from https://www.practicalplaybook.org/success/story/healthy-corner-stores-philadelphias-model-improving-food-access