Outbreaks, Epidemics and Pandemics. What is the Difference?

Many diseases or medical conditions are endemic within a population. The word endemic is derived from Greek words meaning “in the people.” This means an infection has a constant presence within a population.

Outbreaks are noted in geographic regions where there is a sudden increase in the number of people with the disease or condition, above the endemic baseline.

An outbreak becomes an epidemic when it enlarges and becomes more geographically widespread.

Pandemics are conditions when the disease or condition that started in one country has been detected to two or more other countries and is beginning to spread in those countries. Pandemics affect so many people that it is considered to have global impact. The World Health Organization (WHO) declared COVID-19 a pandemic on March 11, 2020.

It is important to remember that these words apply only to the number of people with a disease or condition. They do not refer to the severity of the disease nor to the impact of the condition on individuals. Declaring a disease to be pandemic does not change how threatening it is to individual’s health or the functioning of nations. However, declaring a pandemic opens opportunities nationally and internationally to take the kinds of extensive public health measures necessary to contain or mitigate the disease.