Background
The novel coronavirus pandemic is the perfect model for understanding what exactly a pandemic is and how it impacts life on a global scale. Since the emergence of COVID-19 in 2020, the public has been bombarded with new language to understand the virus and the subsequent global public health response.
What is an Epidemic?
The Centers for Disease Control and Prevention (CDC) describes an epidemic as an unexpected increase in the number of disease cases in a specific geographical area. Yellow fever, smallpox, measles, and polio are prime examples of epidemics. An epidemic disease doesn't necessarily have to be contagious. West Nile fever and the rapid increase in obesity rates are also considered epidemics. Epidemics can refer to a disease or other specific health-related behavior (e.g., smoking) with rates that are clearly above the expected occurrence in a community or region.
What is a Pandemic?
The World Health Organization (WHO) declares a pandemic when a disease’s growth is exponential. This means the growth rate skyrockets, and each day cases grow more than the day prior. In being declared a pandemic, the virus has nothing to do with virology, population immunity, or disease severity. It means a virus covers a wide area, affecting several countries and populations.
What does Endemic mean?
A disease outbreak is endemic when it is consistently present but limited to a particular region. This makes the disease spread and rates predictable. Malaria, for example, is considered endemic in certain countries and regions.
What are the Differences Between Pandemics and Epidemics?
The WHO defines pandemics, epidemics, and endemic diseases based on a disease's rate of spread. Thus, the difference between an epidemic and a pandemic isn't in the severity of the disease, but the degree to which it has spread.
A pandemic cuts across international boundaries, as opposed to regional epidemics. This wide geographical reach is what makes pandemics lead to large-scale social disruption, economic loss, and general hardship. It's important to note that a once-declared epidemic can progress into pandemic status. While an epidemic is large, it is also generally contained or expected in its spread, while a pandemic is international and out of control.
Additional Background Resources:
The World Bank – Putting Pandemics Behind Us: Investing in One Health to Reduce Risks of Emerging Infectious Diseases: https://documents.worldbank.org/en/publication/documents-reports/documentdetail/099530010212241754/p17840200ca7ff098091b7014001a08952e
Pandemics Throughout the History: https://www.cureus.com/articles/69273-pandemics-throughout-the-history#!/