Epidemic vs. Pandemic: How Do We Get From One to the Other?


The terms epidemic vs. pandemic both have a key thing in common: the human race doesn’t want to experience either!

Epidemiologists and virologists have worked overtime over the past few months with the epidemic vs. pandemic question in mind.

On March 11, things changed. For the worst.

That’s when scientists reclassified the novel coronavirus, which people more commonly refer to as COVID-19, as a pandemic.

Before that date, they called it an epidemic after it caused widespread illness in China.

Both are bad.

The pandemic is the really bad one.

So what’s the basic difference? Merriam-Webster explains it this way:

A disease can be declared an epidemic when it spreads over a wide area and many individuals are taken ill at the same time. If the spread escalates further, an epidemic can become a pandemic, which affects an even wider geographical area and a significant portion of the population becomes affected.

That makes it easy to understand.

But when does an epidemic actually qualify for pandemic status? What’s the threshold?

The Centers for Disease Control would be the logical source to ask.

They have an “official” definition for an “epidemic:”

“The occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular period of time.”

Before the epidemic stage, a spread of illness is generally an outbreak. The Slate article from 2003 explains that if that year’s flu deaths reached 7.7 percent of the total deaths that year.

Why 7.7 percent? You can click the link above for the full explanation, but that’s based on a sliding scale that considers how prevalent some illnesses are in a given year.

There’s a reason I wasn’t a math major.

So when does an epidemic become a pandemic?

Again, the CDC has the answer:

A pandemic is a global outbreak of disease. Pandemics happen when a new virus emerges to infect people and can spread between people sustainably. Because there is little to no pre-existing immunity against the new virus, it spreads worldwide.

By March 11, cases of COVID-19 were being reported well outside of China.

By then, according to the World Health Organization, which actually declared it a pandemic, the number of COVID-19 cases outside China jumped 13-fold.

There were more than 118,000 cases in 114 countries, and 4,291 people had lost their lives. 

As of today’s date, just 13 days later, the total cases jumped to 418,099 and the number of deaths rose to 18,608.

Most alarming is that of the “closed” cases, referring to people who either recovered or died, 15% did not survive. That’s not a 15% death rate, because it only counts “closed” cases.

But it’s still a high percentage. The true death rate, comparing total deaths to total cases, open or closed, is about 4.4%.

A few weeks back, however, WHO Director General Tedros Adhanom Ghebreyesus said the then-3.4% mortality rate for COVID-19 was higher than the flu’s global mortality rate.

“Globally, about 3.4% of reported COVID-19 cases have died,” he said. “By comparison, seasonal flu generally kills far fewer than 1% of those infected.”

More than three times deadlier.

That should give pause to everyone who thinks the precautionary school closures and restaurant shutdowns are an overreaction.

And I think you’ll agree that by any reasonable definition, COVID-19 qualifies as a pandemic.

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Patrick is a Christian with more than 29 years experience in professional writing, producing and marketing. His professional background also includes social media, reporting for broadcast television and the web, directing, videography and photography. He enjoys getting to know people over coffee and spending time with his dog.