SAM HARNED

Adjunct professor of history at Washington University in St. Louis.

We sat down with Harned to explore the impact of past pandemics and epidemics on society. Read below for an interesting discussion.


The human race has a long history of fighting illness.

From epidemics (diseases that affect a large number of people within a community, population or region) to pandemics (epidemics that then spread over multiple countries or continents) dating back to ancient times, the world has dealt with diseases and their impacts on populations, society and, not only our history, but also the progress and policies that still impact our world today. Comparing pandemics of the past and those of modern times (including COVID-19) can give us a better understanding of how they happen, how they’ve shaped our history and, ultimately, how they’ve helped drive the advancements in science that protect us from harm.

“One similarity among epidemics and pandemics is that they aren’t random. They tend to occur when existing social, economic, political and environmental features of a community are just right to promote their growth and spread,” says Sam Harned, adjunct professor of history at Washington University in St. Louis. “For instance, three things infectious agents need to spread to pandemic levels include a mobile population, crowded mass conditions and weak or compromised immune systems.”

Looking at the world today—especially here in the United States— Harned points out that ours is a highly mobile and increasingly older population, and many people suffer from pre-existing conditions that make them more susceptible to illness. A major part of the U.S. economy centers around shipping, and significant portions of the nation’s population live in dense urban areas. Harned points out that these facts are reflected in our approach to fighting the current pandemic. “What are the three things we’ve tried to address with COVID-19? Quarantining, social distancing and developing a vaccine,” he says. “This is not to blame people or say pandemics are their fault. This is more about how we have learned to better control pandemics.”

Through the course of history, humanity has faced its share of serious illnesses, which can sometimes have lasting effects that go even beyond medical science.


“Back in 1350, the Bubonic Plague, or Black Death, led to revolutionary change,” Harned says. Considered one of the worst pandemics of all time, it widely spread to wipe out half the population of Europe. “The resulting labor shortage ended feudalism, giving the working population the freedom to escape the restrictions of serfdom.”

The Bubonic Plague also helped lead to the Renaissance, a period of prolific hopefulness, optimism and creativity. Having survived the Plague’s horrors, people found new reasons to celebrate life and the world around them.

There are examples in America’s relatively short history, too—even stretching back to the earliest beginnings as a nation. “As small-pox began to rage up and down the coast during the Revolutionary War,” Harned explains, “George Washington took the daring step of having the Continental Army inoculated in 1777.” Among the troops, 90% of deaths were caused by disease, with smallpox being the worst. Washington even ordered that the local civilian population be inoculated, marking an early example of mass immunization. This saved the Army from the dangers of the smallpox epidemic and allowed the troops to continue the fight for American independence.

Harned shares an additional little-known tidbit: “Even more interesting is the often forgotten Third Amendment to the Constitution,” he says. (The Third Amendment prohibits the quartering of troops in homes.) “It wasn’t just put in place because of the Redcoats barging into your house. The bigger concern was the threat of smallpox they might bring with them.”

Despite the often dark history of epidemics, Harned points out that battling these diseases has resulted in some incredible and life-saving advancements in the medical and scientific fields.

In 1796, English scientist Edward Jenner became a pioneering figure in the use of vaccines when he discovered that exposure to the mild cowpox virus conferred an immunity to smallpox. Nearly two centuries later, Jenner’s discovery not only led to the final eradication of smallpox, but according to Harned, “also paved the way for the use and development of vaccination to address other critical epidemic diseases like polio and measles.”

The threat of pandemics in the 19th century led French scientist Louis Pasteur and German scientist Robert Koch to advance the field of medical microbiology with discoveries concerning the role of microorganisms and germs in disease. Understanding that disease could be caused by microbes—rather than ‘bad air’ in a certain location, the alignment of the stars and planets, or other disease theories—prompted the use of sterile techniques in medical procedures to keep infections from occurring.

Even aspects of our daily lives we sometimes take for granted can have connections to past pandemics. Harned points to one of the 19th century’s greatest killers, cholera, and the resultant advancements in sewage and water treatment. “In its work to eliminate cholera, science ultimately gave us something quite revolutionary: clean tap water and the amazing underground architecture that helps make that possible.”

In what can often be a somber subject, Harned offers this final, positive note. He says, “Whether it’s the determination of the scientific and healthcare community to save lives or the everyday dedication of citizens and family members to care for one another, the history of pandemics tells a story of resilient people who not only persevere, but also move forward with creativity, courage and persistence.”

Pandemics & Epidemics Timeline
1350

The Bubonic Plague

1350

The Bubonic Plague

1492

Arrival of smallpox in the New World

1492

Arrival of smallpox in the New World

1777

Innoculation of the Continental Army against smallpox

1777

Innoculation of the Continental Army against smallpox

1793

Philadelphia Yellow Fever Epidemic

1793

Philadelphia Yellow Fever Epidemic

1798

Creation of the smallpox vaccine

1798

Creation of the smallpox vaccine

1817

First Cholera Pandemic

1817

First Cholera Pandemic

1800s

Tuberculosis is the biggest killer of the 19th century.

1800s

Tuberculosis is the biggest killer of the 19th century.

1906

Typhoid Fever Epidemic in New York City

1906

Typhoid Fever Epidemic in New York City

1916

Major Polio Epidemic

1916

Major Polio Epidemic

1918

Spanish Flu and H1N1 Pandemic

1918

Spanish Flu and H1N1 Pandemic

1955

Approval of Jonas Salk's polio vaccine

1955

Approval of Jonas Salk's polio vaccine

1981

HIV / AIDS Epidemic

1981

HIV / AIDS Epidemic

2003

SARS Pandemic

2003

SARS Pandemic

2019

COVID-19 Pandemic

2019

COVID-19 Pandemic

View a timeline of pandemics and epidemics throughout history.

Table of Contents