In the study of Epidemiology, there are several terms that are used to describe the severity of infections. It is now more important than ever to understand these terms and how to practice the best cautions.

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The terms themselves have been used for a long time in the Epidemiology study. Epidemiology is a medical branch that studies public health disciplines based on quantitative knowledge that includes probability, statistics, and other research methods.

There are 4 terms that are most commonly used to define the condition: Epidemic, Pandemic, Endemic, Outbreak.


The term epidemic is used to describe a disease or infection that has grown out of control. It is also used when a large proportion of people within a region or community has contracted the infection.

Epidemic is often confused with the term Outbreak. While an epidemic refers to an outbreak that is spreading very quickly, out of control, and less localized, an outbreak is seen as a sudden cases in a disease.


While an epidemic is a term used to describe a disease that is currently spreading, Pandemic is used to describe the severity of epidemics that are spreading globally.

There are 6 phases of an influenza pandemic that was designed by the World Health Organization (WHO). These phases were created to map the appropriate response to the disease. However, WHO stopped using these phases as per February 2020.

Here are the 6 phases of pandemics that was designed in 2005:

  • Phase 1 is defined when there is no known evidence of animal transmission
  • Phase 2 is used when domesticated or wild animals are known to circulate the viruses and cause infections in human
  • Phase 3 is used when the viruses spread to a small cluster of communities. However, no human to human transmission is detected yet
  • Phase 4 is marked when there is evidence of human-to-human transmission with possibilities of viruses to cause small outbreaks
  • Phase 5 is a category to describe when the diseases have occurred in two different countries in the same WHO region
  • Phase 6 is used when multiple countries in different WHO regions have confirmed positive for cases

Currently, Covid-19 or coronavirus is classified as a world pandemic by the WHO and the Central for Disease Control and Prevention (CDC).

There are notable pandemics that have happened such as the Spanish Flu, smallpox, the Black Plague, and tuberculosis.


When talking about endemic, malaria is one of the diseases that best describe the term. Endemic is a disease that is seen as a characteristic (or always present) in a population, country, or region.

To understand more on how to best implement individual safety measures, do visit Okadoc blog and constantly check out updated regulations from official health organizations.