Pandemic, epidemic, endemic — what these mean and how they are different from each other

The World Health Organization has finally declared COVID-19 a global pandemic, after months of only referring to the coronavirus outbreak as an epidemic.

File image of a medic checking the temperature of a tourist as part of precautionary screening in the wake of the coronavirus outbreak | Representational image | PTI

New Delhi: After months of only referring to the coronavirus outbreak as an epidemic, the World Health Organization (WHO) Wednesday finally declared it a global pandemic. The virus, that killed over 4,000 and affected more than 118,000 people, has so far spread to six continents and 114 countries.

While officially declaring COVID-19 a pandemic, the WHO had also expressed concern over its “alarming levels of spread and severity” as well as inaction from most governments.

But what does a pandemic mean and how is it different from the terms ‘epidemic’ and ‘endemic’?

Epidemic

An epidemic, as explained by the WHO, is the regional outbreak of an illness that spreads unexpectedly. It refers to an increase, often sudden, in the number of cases of a disease beyond what is normally expected in the population of an area.

Examples of epidemics in India in the past include the outbreaks of zika virus, chikungunya and dengue fever.

The term ‘outbreak’ by definition means the same as an epidemic, but it is often used for a more limited geographic area. ‘Cluster’, on the other hand, refers to an aggregation of cases grouped in place and time that are suspected to be greater than the number expected.

Pandemic

Pandemic refers to an epidemic that has spread across countries and continents — the worldwide spread of a new disease.

“Pandemic is not a word to use lightly or carelessly,” warned Dr Tedros Adhanom Ghebreyesus, director general of the WHO, and claimed the global health body had previously avoided using the term because it didn’t want to give the impression that coronavirus was unstoppable or uncontainable.

Endemic

The term endemic refers to the constant presence and/or usual prevalence of a disease or infectious agent in a population within a geographic area. For example, chickenpox is considered endemic in the UK, but malaria is not.

Hyperendemic refers to the persistent, higher levels of disease prevalence in a particular place.

Why call COVID-19 a pandemic now

After 118,000 positive cases of COVID-19 across 114 countries, it was clear that the virus has surpassed the definition of an epidemic.

Illnesses are often considered pandemic when the disease-causing agent differ from strains currently circulating among humans and has the ability to infect people easily.

Coronavirus has spread swiftly and no vaccines or treatment have been officially found yet. So, declaring it a global pandemic is of urgency to contain its spread.