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Epidemic vs Pandemic vs Endemic: The Main Differences Simply Defined


What is the difference between epidemic vs pandemic? What does endemic mean? In this guide, we break it down for you in an easy-to-understand way.

With the current threat of coronavirus and the increasing number of cases found around the world, people are getting worried, and rightly so.


Wrongly coupling any disease or illness with a word such as epidemic, pandemic, or endemic can cause unwarranted concern and panic.

So, in this post, let’s get academic. We’ll quickly outline the differences between epidemic vs pandemic vs endemic to use them accurately and sparingly.

face masks to protect against epidemic vs pandemic vs endemic
Commuters wearing masks in Tabata Station, Kita-ku, Tokyo, Japan. Taken by Z Ya via unsplash.com. [Public Domain].

Infectious Diseases

Before we talk about the difference between epidemic and pandemic, it’s important to have a basic understanding of infectious diseases.

First, what is a disease?

A disease is a condition which negatively affects a person or other living organism, such as a plant or animal, through a disorder of structure or function.

An infectious disease, sometimes called a communicable disease or transmissible disease, is an illness caused by infection brought on by pathogens (infectious agents). Infectious diseases can be transmitted via viruses (viral disease), bacteria (bacterial disease), fungus (fungal disease), parasites, and some arthropods (ticks, lice, etc.).

Essentially, an infectious disease is one you can catch from someone or something else. A contagious disease is also a type of infectious disease.

There have been several documented coronaviruses so far, but the current version from Wuhan, China is called a novel coronavirus, as it is new to experts. Officially identified as 2019-nCoV, this current coronavirus outbreak is a respiratory virus with symptoms similar to pneumonia.

Did you know? There are also non-infectious diseases, of course, also known as non-communicable diseases, non-transmissible diseases, or non-contagious diseases. Non-infectious diseases are those unable to be transferred from one person to another, such as diabetes, arthritis, Alzheimer’s, cancers, Parkinson’s, and allergies.

For more on China, check out our interesting facts about China, our China travel guide, or our list of facts about the Great Wall of China.


Sorry, we’re getting to endemic vs epidemic vs pandemic, I swear.

Before that, though, what is an outbreak?

An outbreak is a rapid increase in disease occurrence in a particular place and time. Outbreaks can include both infectious and non-infectious diseases, and the nearby and related cases may be called a cluster.

Some places use the term outbreak and epidemic synonymously, but an epidemic is usually much larger in scale. According to some organizations, just four linked cases of an infectious disease is enough to warrant using the term outbreak.

Did you know? Epidemiology is the study of disease conditions in particular populations and the related distribution patterns. Etiology is the study of the causes behind diseases.



What is an epidemic?

An epidemic is the quick expansion of a disease to a large group of people in a short amount of time and in one specific area or region. Usually, an epidemic is when an outbreak expands into a wider population of people.

While epidemics used to only include infectious diseases, it’s now generally accepted to include all diseases with sudden spreading in a given population; for example, an huge uptick in diabetes cases in the Scranton, PA region could be considered an epidemic.

What constitutes an epidemic?

The term epidemic gets applied differently for different infectious diseases. For an outbreak of a disease to be considered an epidemic, it must be found at higher levels than usual for the given population. Also, an epidemic happens when both the transmission agent and susceptible hosts are available in great numbers.

Epidemics may result from:

  • An increase in the virulence of an agent,
  • An increase in the amount of an agent,
  • A new or upgraded method of transmission,
  • New methods of entry,
  • An introduction of an agent into a new environment,
  • A susceptibility change of the agent’s effects on a host.

Did you know? There’s also a syndemic, also known as a synergistic epidemic. A syndemic occurs when there are two or more diseases or afflictions in a population concurrently or sequentially. An example of a syndemic is the SAVA syndemic, an abbreviation of the linked epidemics of substance abuse, violence, and AIDS.


Now, what is a pandemic?

A pandemic is when a disease epidemic spreads much farther from the initial origin, usually into multiple countries and/or continents.

Is the new coronavirus considered a pandemic?

The Wuhan coronavirus (2019-nCoV) has now spread to at least 28 different countries. However, for the most part, all instances of the Wuhan coronavirus in countries other than China are few and contained, so most experts do not yet consider it to be a pandemic. A pandemic might be confirmed if more countries experience epidemic-sized occurrences each.

Though the Wuhan coronavirus is not currently a pandemic, the World Health Organization (WHO) has declared a global health emergency, while still identifying it as an epidemic in mainland China, particularly around the Hubei province. If you’re interested in reading more about the coronavirus, check out the WHO’s website.

Did you know? Two more terms to know are interepidemic and interpandemic. Interepidemic refers to a disease which happens between two identified epidemics, not necessarily connected to either one. Interpandemic refers to something happening between two pandemics.


What is the definition of endemic?

Endemic refers to the persistent or common presence of a disease (both infectious or non-infectious) or an agent of infection in a specific region or population. Endemic is usually an adjective, unlike pandemic and epidemic above.

For example, chickenpox (varicella) is a common occurrence in many countries around the world for school children. In those places, it can’t be considered an epidemic as there is not a sudden increase in chickenpox cases, but rather a persistent presence.

There’s also the term hyperendemic. Hyperendemic refers to high levels of disease occurrence in a region that remain consistent over time. For example, malaria is a hyperendemic disease in many parts of Africa, unfortunately. There, the levels of malaria are brutally high and remain consistently high over time.

Did you know? One more term to know is holoendemic. Holoendemic is when a disease affects just about everyone in a particular population.

Well, that’s our plain-English guide on the difference between pandemic vs epidemic vs endemic and more. We hope you found it easy to understand and helpful! If you have any questions, feedback, corrections, or anything else to add on an epidemic vs pandemic, let us know in the comments below, and thanks for reading!

Want some more difference busters? Check out our articles on the differences between weather vs climate, race vs identity, Spanish vs Hispanic, true north vs magnetic north, and US passports vs passport cards.

Christian Eilers
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Christian Eilers
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