In 18th-century Europe, smallpox was a scourge feared by kings and commoners alike. It was highly contagious, grossly disfiguring, and often fatal. But it was also preventable. Smallpox inoculation—which by then was the norm across Asia and the Middle East—was introduced in the West by Lady Mary Wortley Montagu. Herself a smallpox survivor, the English ambassadress to Turkey had witnessed the practice in Constantinople, and upon her return to England in 1718 she became its biggest advocate. Initially, London society found the practice shocking, but by the end of the century, inoculation had been adopted throughout most of Europe.
But not in France, at least until the king died of smallpox.
One should note that this was very dangerous: before Jenner discovered the mild cowpox could give immunity, they used pus from mild cases of actual smallpox, which not only made you sick but could spread to those around you.
The milliners of Paris, attuned to current events that could be translated into quick profits, commemorated the momentous event with an allegorical headdress dubbed the pouf à l’inoculation. Perched atop a woman’s powdered and pomaded coiffure, it depicted the serpent of Asclepius, representing medicine; a club, representing conquest; a rising sun, representing the king; and a flowering olive branch, symbolizing the peace and joy resulting from the royal inoculation. In commemorating the royal inoculation, the milliners and their female clients helped to publicize it, and the practice—like the pouf—instantly became all the rage.
the story of Washington's order to innoculate soldiers HERE.
most colonials were not immune, but most European adults were.
One reason Canada is not part of the US is because of smallpox, which wiped out the US invasion force.