What is the Role of Epidemiology in Public Health?

Published on: Aug 31, 2023

Core discipline overview: Epidemiology

In a short amount of time, the COVID-19 pandemic transformed the public perception of epidemiologists. Once behind-the-scenes analytical types keeping us safe from biological threats, epidemiologists quickly became recognizable to anyone tuned in to the local news. In fact, employment opportunities in epidemiology are projected to grow 26 percent from 2021 to 2031, which is much faster than the average for all occupations.

In this article, you will learn about the role of epidemiology in public health, what an epidemiologist does, and how you can prepare for a career in public health epidemiology.

What is epidemiology?

Epidemiology is the study of the distribution and determinants (i.e.: causes, risk factors) of diseases and other health-related events in a population. The field of epidemiology is characterized by quantitative methods that help determine how many people have a disease or disorder, how the spread of the ailment is changing over time, how it is affecting society, and how it can be prevented or contained.

In public health education, British doctor John Snow is often hailed the “father of epidemiology”. In the mid 1800s, he proved that a cholera outbreak in a London neighborhood stemmed from contaminated drinking water. This theory differed greatly from the popular medical theories of the time, and Snow was not taken seriously by the general medical community. Now, it’s clear that his methods-- which included identifying those who drank the contaminated water and their disease status, mapping the residences of those afflicted by cholera, and eliminating the suspected contamination source to investigate a change in infection rates-- were the precursors of techniques used in descriptive epidemiology, which describes person, place, and time as they relate to the outbreak, and analytical epidemiology, which involves using experimentation to find a cause and effect relationship.

Today, our understanding of epidemiology extends beyond infectious disease. Diseases studied using epidemiological methods also include non-communicable and chronic conditions, like cancer and cardiovascular disease. Although epidemiologists are commonly referred to as “disease detectives”, epidemiology also involves the study of injury, health treatments, and environmental health hazards, natural disasters, and bioterrorism.

Epidemiology is the study of the distribution and determinants (i.e.: causes, risk factors) of diseases and other health-related events in a population.

Epidemiology in Public Health

According to the CDC framework for essential public health services, epidemiological research supports public health activities related to assessment5. Without monitoring and understanding how diseases spread, we cannot prevent them, and therefore, do the work of public health. Applied epidemiology is a term that is sometimes used to describe the application of epidemiologic principles to address public health issues. Applied epidemiologists work to assess, monitor, investigate and prevent public health problems. They provide crucial information for health promotion, public health policy, and management efforts12.

When epidemiologists describe a public health issue, they do so using statistical methods that help determine the impact on the population level—how many people the disease is affecting, how prevalent it is in the population, and how it affects the quality of life, for example. Some fundamental biostatistics used in epidemiology include:

  • Incidence – the proportion of a population that develops illness during an outbreak

  • Prevalence – the proportion of a population that has a health condition at a point in time

  • Mortality – the frequency of death in a defined population due to a defined health issues during a specified time interval

  • Disability - Adjusted Life Years (DALYs)-- a measure of disease burden that accounts for reduced health status during the lifespan due to the disease

Epidemiology is very closely related to biostatistics, which is the application of statistical methods to health-related information. These methods are used in an epidemiological study to understand disease distribution and health outcomes in a population. However, when it comes to day-to-day job responsibilities, epidemiologists use biostatistical methods to plan studies and monitor diseases, while biostatisticians are primarily responsible for developing and appropriately applying statistical theory.  

To learn more about biostatistics, read “What is Biostatistics?”

What is a public health epidemiologist and what do they do?

Epidemiologists working in public health aim to reduce the spread of disease within a defined geographic area. The geographic scope of their work can vary greatly. For example, a public health epidemiologist working for a city health department may investigate the hotspots of a Hepatitis C outbreak in their city. A global health epidemiologist working with the World Health Organization (WHO) might collaborate with an international health team aiming to eradicate malaria.

Common tasks of a public health epidemiologist include:

  • Data Collection, Management, and Analysis: Epidemiologists conduct research and monitor data to understand how diseases are affecting the human population. Data related tasks include managing large sets of medical data and conducting statistical analyses.

  • Research Design: Epidemiologic studies are the foundation of disease control and prevention. In this career, you can expect to apply epidemiological methods to research. 

  • Interviewing and Contact Tracing: During an active outbreak, epidemiologists contact people in the affected population to understand who has the disease, how they may have contracted it, and provide guidance for preventing spread.

  • Field Observation: Field epidemiologists are deployed during active outbreaks to meet with community members and collect biological samples to identify the health threat.

  • Meetings and Report Writing: Epidemiologists will need to communicate findings to various audiences. 

  • Publishing: Epidemiologists may publish in an academic setting or to provide up to date knowledge on a disease. The CDC’s Morbidity and Mortality Weekly Report (MMWR) is an example of a frequently updated publication meant to disseminate new findings to the public quickly6.

Some epidemiologists may work more closely with big data and have job duties that parallel biostatisticians. In fact, some organizations list a combined “Epidemiologist/Biostatistician” role. Roles with this name often indicate that the role requires a more in-depth knowledge of biostatistical methods, analyses, and software. In other positions, there may be a resident biostatistician that the epidemiologist collaborates with.

Public health epidemiologists can work in different sectors, including government (local and state health departments or federal agencies), clinical research, academia, and private industry.

Follow the links below for ‘day in the life’ content from real public health epidemiologists: 

Day in the Life of a CDC Epidemic Intelligence Officer

Day in the Life of a City Government Epidemiologist

Day in the Life of a WHO Epidemiologist

Why pursue a career in public health epidemiology?

Epidemiology is a career path with a considerable amount of projected growth, and it is a great career for curious problem solvers with strong analytical skills. Salaries for epidemiologists vary greatly depending on industry and years of experience, but compensation is on the higher end of the spectrum for public health professionals. The average nationwide salary for a public health epidemiologist is about $76,000.

Epidemiologists have played a critical role in understanding and containing the COVID-19 pandemic. The pandemic had long-lasting effects on virtually every economic sector, and epidemiologists will continue to serve as experts in disease prevention and public health surveillance. Additionally, many different types of organizations are now thinking about how public health issues impact their workforce. Emergency preparedness and management is an emerging opportunity for public health epidemiologists with an interest and background in health management.  

What skills does an epidemiologist need?

  • Quantitative Methods:

    Analyzing health issues using statistical methods requires strong understanding of quantitative data.

  • Problem-Solving:

    Epidemiologists are often faced with complex issues that do not have straight forward solutions. They must be able to synthesize information from many different sources to inform their recommendations.

  • Data Management and Analysis:

    Epidemiologists regularly use data management systems including Microsoft Excel. Many positions also require proficiency in a statistical or programming software like SAS, STATA, and/or SPSS. More analytical roles may also require proficiency in other programming software, including R and/or Python.

  • Project Management:

    The day to day of an epidemiologist varies greatly. Strong time and project management skills will ensure you can manage any different tasks and responsibilities.

What pros and cons should you be aware of when working in public health epidemiology?

Like what you hear so far about epidemiology? If you are starting to consider this as a career option, you’ll want to consider the pros and cons of a career in epidemiology. Here are a few to consider:



The day-to-day of epidemiologists can have a lot of variety depending on industry, disease focus, and geographic scope.

Variety in work may be less preferable to those who prefer jobs with an established routine and/or similarities across industries.

Higher average pay compared to less quantitative-focused public health careers. 

Workload can increase dramatically during an active public health emergency.

Highly transferrable analytical skills make it easier to pivot into statistical roles within other industries.

Funding for government epidemiology positions is highly affected by health policy. For example, many contract epidemiology jobs were eliminated after the reduction of federal COVID-19 emergency funds. 

How do I start preparing for a career in public health epidemiology?

If being an epidemiologist sounds like it might be the right path for you, you’ll want to start preparing as soon you can. It can take 6 to 8 years to acquire all the education needed for an entry-level epidemiologist role. 

At minimum, you will need an undergraduate degree and a master’s degree. If you are at the undergraduate level, consider choosing a course of study focused on quantitative analytical skills like statistics, mathematics, or biology. However, you can choose any major as long as you complete the prerequisites for MPH Epidemiology programs. For most schools, the requirement is the successful completion of 1 year of college level math and science. 

When you are selecting a program, make sure that you choose a program that has comprehensive coursework options. This includes a mix of epidemiological methods and theory and elective disease-specific courses. If you have a specific interest in a certain topic area, such as maternal and child health, review MPH course offerings of your school of choice to make sure they have courses in that area. Also pay attention to the software–based courses offered. It is much easier to learn SAS, SPSS, and STATA in school– their costs and licensing procedures can make them difficult to access and learn on your own. If you prefer learning a certain type of software, review your target school’s course offerings to see if it is offered. 

While the typical epidemiologist isn’t always jetting around the world to be at the frontlines of a disease outbreak, they still play a crucial role in protecting humanity from health threats. If you are excited about the prospect of becoming a disease detective, take the first by finding the right Master’s in Epidemiology program for you.

About the Authors

Written by:

Wandia Mureithi, MPH

Wandia Mureithi, MPH is a public health project manager working in research and evaluation. Wandia received her Master’s in Public Health from Drexel University in 2022. Since beginning her career in 2018, she has been engaged in research projects and program evaluations related to sexual health, human trafficking prevention, tobacco prevention, opioid misuse treatment, and diabetes prevention. 

In addition to her work projects, Wandia is interested in reducing maternal and child health disparities and advancing social justice in public health. 

Opinions and information published by the author here on MastersPublicHealth.com are of my own and do not necessarily represent the views or opinions of my employer or other organizations for my designated roles.

Wandia Mureithi portrait photograph

Wandia Mureithi, MPH

Education: Drexel University Dornsife School of Public Health

Reviewed by:

Katherine Paul, MPH

Katherine Paul, MPH is a senior project manager at a leading medical communications and publications organization. She supports multidisciplinary teams handling large-scale accounts, the deliverables of which improve health outcomes and patient well-being. Ms. Paul holds a Master of Public Health (MPH) degree in Health Promotion from Columbia University, Mailman School of Public Health and passed the Certified Health Education Specialist (CHES) shortly after graduation. She holds a Bachelor of Arts degree in Sociology from Dickinson College.

Ms. Paul previously worked at a public health non-profit where she managed all aspects of diverse health-related projects, including the implementation of a randomized controlled clinical trial on sexual health for teens with developmental disabilities, as well as the evaluation of a statewide tobacco cessation program with more than 20,000 annual cases. She has developed and delivered posters and presentations at national conferences including the American Public Health Association (APHA) annual meeting. 

Opinions and information published by the author here on MastersPublicHealth.com are of my own and do not necessarily represent the views or opinions of my employer or other organizations for my designated roles.

Katherine Paul

Katherine Paul, MPH

Editorial Lead

Education: Columbia University, Mailman School of Public Health

Dive Deeper in Research

stack of books icon

What Areas Exist Within Public Health, Where to Start, And Where Do You Fit In?

Given the broad applicability of an MPH or other professional public health degree (including an undergraduate public health major), there are a multitude of avenues one might be interested in when drawn to public health. 

statistics and biology icon

What is Biostatistics?

In this article, you’ll learn about the role of biostatistics in public health and how to pursue a career in biostatistics. 

heart with money symbol icon

What is Health Economics?

In a broad sense, economics is the study of decisions, the incentives that lead to them, and the various consequences of those decisions. But how does this apply to public health? This is where the essential role of a health economist comes into play. Read on to learn more about this topic and its imperative role in public health.