Saturday, April 25, 2020

Past Pandemics

Credit: National Museum of Health and Medicine, public domain, source.

How does the current COVID-19 pandemic compare to past pandemics? Let's take a look.

The Black Death (14th century)

The Black Death was the worst pandemic in recorded history, resulting in 75-200 million deaths worldwide. Europe was particularly hard hit, losing 30-60% of its population. The pandemic peaked in Europe from 1347 to 1351. (Wikipedia) For this post I am using 100 million deaths and a world population of 400 million, for a death rate of 25%.

The disease of the Black Death pandemic was the plague. It is caused by a bacterium carried by fleas living on rats. Transmission is mainly by flea bites or handling infected animals, and secondarily through the air from the coughing of infected individuals.

Influenza Pandemic of 1918

The influenza pandemic of 1918 killed an estimated 50 million people worldwide (National Archives). Other estimates of the death toll range from 17 to 100 million people worldwide and 500,000 to 850,000 in the U.S. (Wikipedia). For this post I am using 50 million deaths worldwide and 675,000 in the U.S.

The pandemic occurred in waves. The first wave was in early 1918 and was relatively mild. The second, deadly, wave occurred in the fall of 1918 as World War I was ending. Lesser outbreaks continued into 1920.

While plague is caused by a bacterium, influenza (aka "the flu") is caused by a virus. There are many different influenza viruses. The 1918 flu pandemic was caused by the H1N1 influenza virus. Transmission of the flu is mainly through the air.

The photo above shows patients in an emergency hospital at Camp Funston, part of Fort Riley, Kansas, in the midst of the 1918 influenza pandemic. The photo is part of the Otis Historical Archives at the National Museum of Health and Medicine.

The influenza pandemic of 1918 is sometimes called the Spanish flu, but this is a misnomer as explained here.

Influenza Pandemics Since 1918

The U.S. Centers for Disease Control and Prevention (CDC) lists three smaller influenza pandemics since 1918 (source):
  • 1957 influenza pandemic, also called the Asian flu (H2N2 virus) – estimated deaths 1.1 million worldwide; 116,000 in the U.S.
  • 1968 influenza pandemic, also called the Hong Kong flu (H3N2 virus) – estimated deaths 1 million worldwide; 100,000 in the U.S.
  • 2009 influenza pandemic, also called swine flu (H1N1 virus, but a different strain from the 1918 flu pandemic) – estimated deaths 150,000-575,000 worldwide; 12,500 in the U.S. For this post I am using a figure of 400,000 deaths worldwide.
Comparison to the COVID-19 Pandemic

The current pandemic is caused by a coronavirus, which is a different group of viruses from influenza viruses. Like the flu, however, COVID-19 is spread primarily through the air.

As I write this, there have been approximately 200,000 deaths worldwide (source); approximately 50,000 deaths in the U.S. (source); and 44 deaths in Vermont (source). Comparable statistics for earlier dates: March 26 and April 4.

Here is a comparison of the worldwide deaths (click on any image to enlarge):

The pandemics of the last 65 years look insignificant compared to the Black Death and the 1918 flu pandemic. The disparity is even greater when considered as a percentage of world population, as shown in the following table:

[World population numbers from here (historical) and here (current). I did some rounding.]

Now let's look at just the pandemics of the last 65 years (i.e., excluding the Black Death and the 1918 flu pandemic) and include the U.S. numbers. The following graph shows total deaths, not as a percentage of population:

On a worldwide basis, total deaths to date from the current coronavirus pandemic are approximately half of the 2009 pandemic and do not yet approach the pandemics of 1957 and 1968. In the United States, however, COVID-19 deaths to date are four times the deaths from the 2009 flu and approximately half of the deaths from the 1957 and 1968 flus.

As we think about the future we should keep in mind that, like the influenza pandemic of 1918, there may be more than one wave of the current COVID-19 pandemic.

Saturday, April 4, 2020

We are in a war

When I am stressed, I sometimes remind myself that at least I'm not in a war, that no one is shooting real bullets at me. I've never been in a real shooting war, but we are all in a war now. A war against a novel (new) coronavirus known as SARS-CoV-2. This is the enemy:

In unprecedented times such as these, we reach for analogies to help us understand the new reality around us. In this post I recommend two videos that offer analogies that I find helpful.

In the first video, the speaker says "this is a Dunkirk moment for our country." That's an analogy I can understand. While I have not watched the 2017 movie Dunkirk, I know the basic story of this pivotal moment in World War II.

(3/24/2020, 14 minutes, alternate link)

This video is an interview with Anthony Monaco, the president of Tufts University. Dr. Monaco, a geneticist, describes the transformation of parts of the Tufts University campus into a military-style hospital to fight the war against coronavirus. The Dunkirk analogy is in the answer to the question asked by the interviewer at 9:40.

[Local readers may be interested in how I learned about this video. I reached out to Jessica Daniels to see how she was doing during this pandemic. Jessica lives in Cambridge, Massachusetts, and she is engaged in a quest to visit and blog about other Cambridges in the United States. She visited Cambridge, Vermont, last September. Click here for what she wrote about our town. It's interesting and insightful. Anyway, Jessica works at Tufts University and she told me about the video.]

The second video I recommend is about safely buying groceries and take-out food.

(3/24/2020, 14 minutes, alternate link)

This video is by Dr. Jeffrey VanWingen, an MD in Michigan. I've linked to this video before, but it's worth highlighting again. As I write this, it has been watched nearly 25 million times.

Dr. VanWingen offers another useful analogy: glitter. Think of the virus as glitter, except that it is invisible. It sticks to everything and it may be anywhere. Your job is to keep it out of your house, off your person, and especially out of your respiratory system.

Other differences between real glitter and the coronavirus:
  • Coronavirus is destroyed by soap. Wash your hands!
  • Coronavirus decays over time.
  • Coronavirus floats in the air and is stable in air for up to 3 hours (longer on surfaces). (link)
The last item is a problem, because infected people exhale the virus. (link) Person-to-person transmission through the air is thought to be the most common way the disease spreads. This is a BIG problem because an infected person may not show any symptoms. They may not know they are infected. That is why social distancing and six feet of separation are important.

Stay at home as much as possible. Hunker down. When you must go out in public, assume that everyone you meet is infected even if they are not showing symptoms, and assume that you are infected even if not showing symptoms.

Wear a cloth face mask in public. (Not an N95 mask. Those are scarce and need to be reserved for professionals.) A cloth face mask provides a small amount of protection for the wearer. More importantly it protects the people around us in case we are an asymptomatic carrier. (The State of Vermont recommends cloth face masks) (Making cloth face masks in Vermont)

It is hard to fight a war against something we can't see, but perhaps the analogies of Dunkirk and glitter will help us understand the new reality facing us.

War Casualties

As I write this, there have been more than 60,000 deaths worldwide (source); more than 5,000 deaths in the U.S. (source); and 17 deaths in Vermont (source). See this earlier post for comparable statistics as of March 26. Sadly the first COVID-19 death of a Cambridge resident has occurred (source).