What is a Pandemic?

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Whenever a new disease emerges, the term “pandemic” is very commonly heard on the news and social media. However, its definition is not always clear. Briefly, a pandemic occurs when a new disease spreads widely across multiple areas of the world. There are some key characteristics that separate a pandemic from other epidemiological terms, such as endemics and epidemics; experts declare a pandemic when a) the infectious agent (e.g. a virus) causing the disease is entirely new or sufficiently different from existing ones, b) the number of cases in each area exceeds what is expected based on the population (i.e., an outbreak), and c) there are increased occurrences in various parts of the world simultaneously.

virus 3d illustrationThere have been various pandemics throughout history, such as the plague, the Spanish flu, etc. Although pandemics can be caused by any highly infectious agent, most recent instances are associated with novel strains of the influenza virus, which causes the flu. The influenza virus mutates constantly and is highly infectious, which is why many pandemics are caused by it. For example, the 2009 H1N1 pandemic was caused by a new strain of the Influenza A virus. This strain had many differences when compared to the seasonal flu strains, which were sufficient to render the existing flu vaccine mostly ineffective, and required the development of a specialized vaccine.

Nowadays, most countries have emergency preparedness plans for the possibility of future pandemics. However, there are also some simple things we can all do to limit the spread of disease and infection, such as washing our hands frequently, avoiding contact with sick individuals, and covering our cough and sneeze using the inside of our elbow.

More pandemic resources

  1. World Health Organization. https://www.who.int/csr/disease/swineflu/frequently_asked_questions/pandemic/en/

  2. Centers for Disease Control and Prevention. https://www.cdc.gov/flu/pandemic-resources/basics/index.html

  3. Ready.gov – Department of Homeland Security https://www.ready.gov/pandemic

— Vicky Kanta