Print Friendly, PDF & Email





The coronavirus outbreak that began late last year in China has now spread to 29 countries, touching every continent except South America and Antarctica. While most of these cases are still in China, the virus is gaining a foothold in other countries, raising fears that the world is on the brink of a pandemic. All pandemics start with an outbreak of a new disease in a specific geographic location. If that outbreak becomes larger, but still remains confined to a specific region, it becomes an epidemic. At that point, the WHO may declare a public health emergency of international concern to raise awareness about it. But once a disease spreads globally, with multiple epidemics across different continents, it truly becomes a pandemic.

What is Pandemic?

  • A pandemic is an epidemic of disease that has spread across a large region; for instance multiple continents, or worldwide.
  • A widespread endemic disease that is stable in terms of how many people are getting sick from it is not a pandemic.
  • Further, flu pandemics generally exclude recurrences of seasonal flu.
  • Throughout history, there have been a number of pandemics, such as smallpox and tuberculosis. One of the most devastating pandemics was the Black Death, which killed an estimated 75–200 million people in the 14th century.
  • The only current pandemic is HIV/AIDS, which started in the 1980s. Other recent pandemics are the 1918 influenza pandemic (Spanish flu) and the 2009 flu pandemic (H1N1).

In the grand scheme of things, a pandemic is the highest possible level of disease, or a measure of how many people have gotten sick from a particular disease and how far it has spread—but before a common illness reaches pandemic proportions, it has to exceed a few other levels, according to the Centers for Disease Control and Prevention (CDC):

  • Sporadic: When a disease occurs infrequently and irregularly.
  • Endemic: A constant presence and/or usual prevalence of a disease or infection within a geographic area. (Hyperendemic, is a situation in which there are persistent, high levels of disease occurrence.)
  • Epidemic: A sudden increase in the number of cases of a disease—more than what’s typically expected for the population in that area.
  • Pandemic: An epidemic that has spread over several countries or continents, affecting a large number of people.

Biggest Pandemics:

There have been a number of significant epidemics and pandemics recorded in human history, generally zoonoses which came about with the domestication of animals, such as influenza and tuberculosis. There have been a number of particularly significant epidemics that deserve mention above the “mere” destruction of cities:

  • Plague of Athens, from 430 to 426 BC. During the Peloponnesian War, typhoid fever killed a quarter of the Athenian troops, and a quarter of the population over four years. This disease fatally weakened the dominance of Athens, but the sheer virulence of the disease prevented its wider spread; i.e. it killed off its hosts at a rate faster than they could spread it. The exact cause of the plague was unknown for many years
  • Antonine Plague, from 165 to 180 AD. Possibly smallpox brought to the Italian peninsula by soldiers returning from the Near East; it killed a quarter of those infected, and up to five million in all.
  • Plague of Justinian, from 541 to 750, was the first recorded outbreak of the bubonic plague. It started in Egypt, and reached Constantinople the following spring, killing (according to the Byzantine chronicler Procopius) 10,000 a day at its height, and perhaps 40% of the city’s inhabitants.
  • Black Death, from 1331 to 1353. The total number of deaths worldwide is estimated at 75 million people. Eight hundred years after the last outbreak, the plague returned to Europe. Starting in Asia, the disease reached Mediterranean and western Europe in 1348 and killed an estimated 20 to 30 million Europeans in six years; a third of the total population, and up to a half in the worst-affected urban areas. It was the first of a cycle of European plague epidemics that continued until the 18th century.
  • Spanish flu, from 1918 to 1920. It infected 500 million people around the world, including people on remote Pacific islands and in the Arctic, and resulted in the deaths of 50 to 100 million people. Most influenza outbreaks disproportionately kill the very young and the very old, with higher survival rate for those in between, but the Spanish flu had an unusually high mortality rate for young adults. Spanish flu killed more people than World War I did and it killed more people in 25 weeks than AIDS did in its first 25 years. Mass troop movements and close quarters during World War I caused it to spread and mutate faster; the susceptibility of soldiers to Spanish flu might have been increased due to stress, malnourishment and chemical attacks. Improved transportation systems made it easier for soldiers, sailors, and civilian travelers to spread the disease

Phases of Pandemics:

The World Health Organization (WHO) provides an influenza pandemic alert system, with a scale ranging from Phase 1 (a low risk of a flu pandemic) to Phase 6 (a full-blown pandemic):

  • Phase 1: A virus in animals has caused no known infections in humans.
  • Phase 2: An animal flu virus has caused infection in humans.
  • Phase 3: Sporadic cases or small clusters of disease occur in humans. Human-to-human transmission, if any, is insufficient to cause community-level outbreaks.
  • Phase 4: The risk for a pandemic is greatly increased but not certain.
  • Phase 5: Spread of disease between humans is occurring in more than one country of one WHO region.
  • Phase 6: Community-level outbreaks are in at least one additional country in a different WHO region from phase 5. A global pandemic is under way.

Prevention tips:

In the event of a pandemic, follow the advice of public health authorities, and the instructions issued in your work environment.

  • Take advantage of the vaccine as soon as it is offered, in order to protect yourself and those close to you, and not contribute to the spread of the disease among the general population.
  • Wash your hands often with soap and water or rub them with an alcohol-based antiseptic gel, foam or liquid. Keep such products out of the reach of children. Also frequently clean your living environment with soap and water or household detergents.
  • Cough and sneeze without contaminating your environment and avoid touching your nose, eyes and mouth, which are the gateways of virus in the body.
  • Avoid contact with sick people and their personal items. If you have to take care of a sick person, protect yourself from the secretions, and do not drink water or eat food that had been in contact with this person.
  • Avoid contact with animals that appear sick, and avoid handling animals that are found dead.