Pandemic

A plague doctor wearing the special costume of such doctors at the time. The costume was thought to protect the wearer against the plague.  If it seems weirdly creepy, it's probably just about as effective as wearing a surgical mask in a public place.

Pandemic:

A pandemic is the worldwide spread of a new disease.

World Health Organization.

An epidemic of disease, or other health condition, that occurs over a widespread area (multiple countries or continents) and usually affects a sizeable part of the population.

U.S. Department of Health and Human Services.

Pandemic refers to an epidemic that has spread over several countries or continents, usually affecting a large number of people.

U.S. Center for Disease Control.

Pandemic: An epidemic (a sudden outbreak) that becomes very widespread and affects a whole region, a continent, or the world due to a susceptible population. By definition, a true pandemic causes a high degree of mortality (death) 

By contrast:  

• An epidemic affects more than the expected number of cases of disease occurring in a community or region during a given period of time. A sudden severe outbreak within a region or a group as, for example, AIDS in Africa or AIDS in intravenous drug users. 
• An endemic is present in a community at all times but in low frequency. An endemic is continuous as in the case of malaria in some areas of the world or as with illicit drugs in some neighborhoods. 

The word "pandemic" comes from the Greek "pan-", "all" + "demos," "people or population" = "pandemos" = "all the people." A pandemic affects all (nearly all) of the people. By contrast, "epi-" means "upon." An epidemic is visited upon the people. And "en-" means "in." An endemic is in the people.

Web MD*

Is there a Coronavirus epidemic and if there is, will it become a pandemic?

It's certainly creating havoc on the world economic scale, but a lot of that is due to human reaction rather than the disease itself.  Faced with a new disease that seemed to have a high incidence of fatality, the People's Republic of China struggled to get ahead of the disease and for a time, frankly, did badly, resorting to shutting information up, the usual reaction of a Communist state to any bad news of any kind whatsoever.  After that, exhibiting massive control of the population, it managed to shut things down.

That had an impact on the world's economy as it was.  China has become the manufacturing hub, unfortunately, for the globe, relying on cheap labor and a well educated population as it does.  So the virtual closing of a region of the giant country had an immediate ripple effect on the economy of the planet.  But only a ripple.

Which is temporarily beside the point in this post.

Humans retain an interesting memory, sort of, of historic pandemics.  In our collective memories, they occur, but our memory of them is quite flawed. Almost by definition we imagine all pandemics to be real killers, and we have been worrying that Coronavirus will break out as a killer pandemic.

Here on this site we're somewhat uniquely situated as we deal with, the past two years, the 1918-19 Influenza Pandemic, which was a real killer that swept the globe to massive effect.  Millions died in that event, which had a 2.5% mortality rate.

Yes, 2.5%.

That doesn't sound that high, but a normal variant of the flu has a less than .1% mortality rate. The flu still kills thousands in the U.S. every year, but it didn't have the impact that the 1918-19 flu did.

The pandemic, however, that really remains vaguely in our memory was the Great Plague, which killed 30% to 60% of the European population and which is estimated to have reduced the human population by about 500,000,000 people globally.  Raging from 1347 to 1351, the pandemic actually trailed all the way into the 20th Century, contrary to popular understanding of it, and is actually within the vague life experience of quite a few living people.  Regions of the globe in some instances didn't recover until the 19th Century. 

Of course, we need to keep in mind a couple of things about both of these. First of all, living conditions contributed a lot to the Great Plague. It's flea borne disease, after all.  Today, the plague, which is still around, isn't nearly as deadly as we don't live in a sea of fleas.

In the 1340s, we did.

When you hear of somebody getting the plague and dying of it today, and you do if you pay careful attention, it's because they did something that put them in contact with fleas.  Hunters will occasionally get them from game, and I recall reading in a National Geographic about a rural hiker getting it just because of where he walked his dog.

In contrast, the most recent disease to clearly achieve the widespread dread level, AIDS, may or may not have ever been a pandemic, but because of its mode of transmission was actually fairly difficult to get.  The plague put the entire 14th Century human population at risk because of the way they lived and had to live.  AIDS actually only put a narrow demographic at risks due to a variety of things, all of which except for blood borne transfusions, had an element of human conduct involved to them.  I'm not cast aspersions of any kind here, but only noting the science of it.

The 1918 Flu, however, was an airborne disease that people simply couldn't avoid.  The conditions of World War One, including crowded troop conditions, massively contributed to its spread, as did the transportation of troops around the globe. But the disease itself was airborne.

So is the Coronavirus, and like the 1918 flu, it got started in crowed conditions (and in Asian conditions, like most flus do) and its being transported around the globe due to travel, the difference being that its getting around a lot quicker than the 1918 flu did.

The mortality rate of the Coronavirus isn't known yet.  Early reports in China placed it at 17%, which is massive.  If that was the rate, the globe would really be in for it as this would truthfully be an airborne disease the likes of which we haven't seen for a very long time.  More recent data, however, roughly came in at about 3%, and then 2%.  In comparison the the death rates for SARS is 9.6%, MERS 34% and the Swine Flu, which was a bad one, .02%

The disease is distinctly different than the flu in a lot of ways, which is important to note.  The flu takes a trip through ducks and pigs on its way to humans, for one thing, while the Coronavirus takes a trip through bats.  That's bad as bats have a titanic immune system and that means that the virus doesn't terminate there for that reason.

Additionally, the flu is a family of nasty diseases where as this Coronavirus is just one, COVID-19. 

Like the flu, however, people's reactions vary and apparently 81% of those who get Coronavirus get a mild form of it.  Some show hardly any reaction to it at all. That's good as chances are if you get it, it'll be mild.  It's hardest on the elderly, which is the case for the normal flu (but which was not the case for the 1918-19 flu which hit the young hardest).  And it may turn out to be that it's less deadly than it currently appears to be.  Frankly the fact that it was an unknown disease when it hit and that only the severely ill were reporting to hospitals made it initially appear worse than it was.

Having said that, even if its half as deadly as it currently appears, it'll still kill a lot of people who get infected.

And frankly, from a scientific prospective, my guess is you are going to get it. 

A recent Harvard report put the floor of the infection at 40% of the human population, and the ceiling at 60%, which is less than the 1918 flu ultimately infected.  I'd guess that to be right, no matter what.

And that does mean that this is going to impact the economy.  It'll do it only temporarily.  Taking the 1918-1919 flu as the most analogous example is difficult, however, as World War War was raging during its worst months, which made its economic impact muted; people kept fighting and kept making munitions, etc., as they had to.  Having said that, the flu did basically take the Australian Army in Europe out of the war in the fall of 1918, which was towards the war's end, and it may have had an impact on the German 1918 spring offensive.  Had the war not been raging, the economic impact would have been notable, but then if the war hadn't been raging, the flu likely wouldn't have turned into a pandemic. So it turns out that it's not a very good analogy.  Indeed, one Federal researcher who studied it concluded:**

The influenza of 1918 was short-lived and “had a permanent influence not on the collectivities but on the atoms of human society – individuals.”31 Society as a whole recovered from the 1918 influenza quickly, but individuals who were affected by the influenza had their lives changed forever. Given our highly mobile and connected society, any future influenza pandemic is likely to be more severe in its reach, and perhaps in its virulence, than the 1918 influenza despite improvements in health care over the past 90 years. Perhaps lessons learned from the past can help mitigate the severity of any future pandemic

And so, this isn't a cheery post.  My guess is that this disease,  now that the evidence is in, will get around, and it will kill quite a few.  It won't be like the Great Plague, thank goodness, but it'll be a disaster for some, and it will be a damper on the global economy until the spring.

*FWIW, the best of these definitions is the Web MD one.
**Economic Effects of the 1918 Influenza Pandemic Implications for a Modern-day Pandemic Thomas A. Garrett Assistant Vice President and Economist Federal Reserve Bank of St. Louis