Epidemiology is the study of the emergence, distribution, and control of disease, disability, and death among groups of people. It's a field that combines elements of biology, clinical medicine, sociology, mathematics, and ecology to identify and understand health patterns and improve human health across the globe. Epidemiologists are doctors and scientists who work to understand the source of disease and other negative health effects.
They estimate how many people are exposed and how the disease spreads. Epidemiologists are generally associated with infectious diseases and outbreaks, such as the COVID-19 pandemic, but they also study non-infectious health problems, like the prevalence of lung cancer from smoking or a community's increase in homicide rates. The epidemiologic triangle is a tool epidemiologists use for explaining the connection between the cause of a disease and the conditions that allow it to spread.
The triangle's three corners represent the who, what, and where of a disease. Who is the host or person or people who has the disease? What is the agent or cause of the disease? And where or in what environment does the disease occur?
The goal of an epidemiologist is to figure out how to sever at least one link between the corners of that triangle. Breaking the connection between the host, agent, and environment stops the disease in its tracks. In early March 2020, during the COVID-19 pandemic, epidemiologists from Imperial College London released a model showing the potential impacts of the disease if certain prevention methods were implemented or not.
The scientists recommended large-scale social distancing to slow the spread of the virus and prevent millions of people from dying, thus severing the connection between the where and the who. The team's recommendations became public policy in many parts of the world and will result in fewer cases of the disease than expected had the triangle remained intact.