Overview: Pandemics

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Author: Dr. Ronald St. John

Throughout history there have been outbreaks of infectious diseases. The well-known plague epidemic (Black Death) was a devastating global epidemic of bubonic plague that struck Europe and Asia in the mid-1300s, wiping out an estimated one-third of the population. Disease outbreaks, when large in scope, have been referred to as epidemics. More recently, epidemics that have involved or might involve the global population have been labelled as pandemics.

When does an epidemic become a pandemic? There is no single accepted definition of the term pandemic (ref: Journal of Infectious Diseases, Vol. 200:7, 1 October 2009). Some considerations for labelling an outbreak as a pandemic include outbreaks of diseases:

  • that extend over large geographic areas, e.g., influenza, HIV/AIDS
  • that have high attack rates and explosiveness, e.g., common-source acquisition and highly contagious diseases with short incubation periods
  • that affect populations with minimal population immunity
  • that involve a new or novel version of an infectious agent – the term pandemic has been used most commonly to describe diseases that are new, or at least associated with novel variants of existing organisms, e.g., influenza.
  • that are highly contagious. Many, if not most, infectious diseases considered to be pandemic by public health officials are contagious from person to person
  • that have severe health consequences. The term pandemic has been applied to severe or fatal diseases

For purposes of this paper, a pandemic is an epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people.(1)

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Adam Wynne

I am shocked China and other surrounding nations are not implementing stricter travel guidelines right now – given the upcoming Chinese New Year celebrations and the newly emerged coronavirus. Is the massive influx of travelers worth the potential of another SARS-like epidemic? Millions of individuals will be arriving to a region with a still emerging infectious disease. Hopefully enough is understood about the new coronavirus to limit its spread during this festive time of year. It must be a difficult finding a balance between cultural tradition and public health. The World Health Organization is scheduling an emergency meeting (in Geneva)… Read more »

Adele Buckley

Important news relating to pandemics has been published by the Nuclear Threat Initiative. It says ” The Global Health Security (GHS) Index, a benchmark assessment of biosecurity preparedness across 195 countries produced by NTI and the Johns Hopkins Center for Health Security, is earning news media attention around the world in the wake of its recent launch. A Washington Post article on the index highlighted its findings and recommendations, and the paper’s editorial board noted that “the world flunked.” The GHS Index also has garnered coverage across 14 countries including reports in the UK’s Daily Mail, Singapore’s The Strait Times… Read more »

Report says deadly pandemic could sweep world in 36 hours – killing millions New Zealand Herald, 26 Oct, 2019 5:15pm A major new report has found that the world is not prepared for the next global pandemic. A review of health care systems already in place across the world found just 13 countries had the resources to put up a fight against an “inevitable” pandemic. Scientists warned that an outbreak of a flu-like illness could sweep across the planet in 36 hours and kill tens of millions due to our constantly-travelling population. Among the countries ranked in the top tier… Read more »


“Inaugural Global Health Security Index Identifies Major Gaps in Preparedness for Epidemics, Pandemics” Nuclear Threat Initiative News, Oct 24, 2019. Despite growing risks that infectious disease outbreaks can lead to international epidemics and pandemics, national health security is fundamentally weak around the world, and no country is fully prepared to handle a potentially catastrophic outbreak, according to the inaugural Global Health Security (GHS) Index released today. A joint project from the Nuclear Threat Initiative (NTI) and the Johns Hopkins Center for Global Health Security, with research by The Economist Intelligence Unit (EIU), the GHS Index is the first comprehensive assessment… Read more »