Humanity have lead through some truly devastating pandemics that have killed hundreds of thousands to millions of people.
According to the World Health Organisation, a pandemic is “an epidemic occurring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people.”

13 women explain why they date men with the Bubonic Plague - Vox

Leprosy was one of the earliest pandemics,Ever Recorded, spreading through Europe in the Middle Ages.

Leprosy, which reached pandemic levels in the 11th century, is one of history’s most misunderstood diseases. For centuries, people believed the disease was hereditary and even served as a punishment from God.

 Patients were stigmatised and exiled. When they weren’t banished from society, they had to wear special clothing and even ring bells to let others know they were coming.
The extreme fear of the disease was due to one of its symptoms, tissue necrosis, in which parts or entire limbs turn black.
However, the disease has been curable since 1981, when the WHO recommended multi-drug therapy (MDT) to treat leprosy patients. 

What past pandemics can teach us about responding to coronavirus ...

The Black Death, also known as the bubonic plague, killed one-third of Europe’s population in the 14th century.

The Black Death is believed to have killed about 25 million people, spreading through Europe and Asia on the backs of fleas and rats.

 It was discovered in Europe in 1347 after a ship docked at a Sicilian harbour. The ship was carrying dead sailors along with those who were barely alive, covered in boils oozing pus and blood. Other symptoms included fever, chills, vomiting, diarrhoea, aches and pains, and eventually death.

Several classes of antibiotics (aminoglycosides such as streptomycin and gentamicin) are effective in treating bubonic plague.

Caring for Spanish flu victims | 1919: American Red Cross vo… | Flickr

Spanish Flu: 1918-1920 Despite the name Spanish Flu, the disease likely did not start in Spain. The Spanish flu was an avian-borne illness that killed more than 50 million worldwide.The Spanish flu in 1918 was the deadliest pandemic in history, killing 50 million people worldwide, and infecting an estimated 500 million, or one third of the world population at the time.
There were no effective drugs or treatments for the disease. Instead, people were ordered to wear masks, and all schools, businesses and theaters were closed.
The disease was so severe that victims could sometimes die within hours or days of showing symptoms.