Some diseases are always present in a population, while others come and go. The difference between these two types of diseases is important to public health, as it can help guide the best ways to monitor and treat them.
The word “pandemic” was originally used to describe a disease that had spread across an entire region or even the world. The pandemic of 1918, for example, killed at least 50 million people worldwide. Today, the term has come to mean something a little different. The World Health Organization (WHO) defines a pandemic as “the worldwide spread of a new disease.” This is also the case for COVID-19 and now many experts hope that the virus will soon enter its endemic phase.
Pandemic vs. endemic: What’s the difference?
We often hear the terms pandemic and epidemic used interchangeably. But they are not synonymous.
When we talk about a disease outbreak, we are referring to a rise in cases of that disease above what is normally expected. Depending on how many people become sick and how widely the disease spreads, an outbreak can be classified as an epidemic, a pandemic, or neither.
Pandemic refers to an epidemic occurring over a wide geographic area and affecting an exceptionally high proportion of the population — for example, a worldwide flu outbreak.
An epidemic occurs when an infectious disease spreads within a community or region. An epidemic can also refer to any situation that affects many people within a population at the same time. For example, people sometimes refer to certain drug epidemics or crime epidemics.
You might also hear the word “endemic” used when people are talking about diseases. The difference between an endemic disease and an epidemic or pandemic is that endemic diseases occur regularly in certain locations. For example, malaria is endemic to tropical areas, while seasonal flu outbreaks are endemic in colder areas.