So, continuing.  Smallpox was around for a long time, until about 1979, when the World Health Organization declared the disease completely eradicated.  Who can you thank for this? Edward Jenner.

The above Wikipedia link is extensive, so here’s what he did, simplified.  Really, it was simple.  It was known during Jenner’s time that cowpox (a Vaccinia virus) could impart immunity to smallpox (a Variola virus) by innoculation, but nobody knew how.  Mankind got incredibly lucky, hence my title.  Jenner hypothesized that pus from a cowpox pustule did the trick.  That’s because milkmaids were known to be immune to smallpox.  Here’s an engraving of a cow utter with cowpox.  Lovely isn’t it?  (The pictures are from the Wellcome Image Library, and I encourage you to explore the site.)

So, Jenner took a pointy ivory stick

stuck it into a cowpox pustule from a milkmaid, and scraped the pus into the skin of his gardener’s son.  Lucky him – lucky for us.  (The Dowager might have approved the working class being guinea pigs, but I digress.)  After recovering from the cowpox illness, Jenner purposely infected the boy with smallpox.  This is known in modern medicine as a “challenge,” but was not out of the ordinary back then.  It was common to infect people with smallpox on purpose so they’d be immune when the next epidemic hit.  Life was a bitch, for sure.

This seems horrible to a modern sensibility. But this is just risk management, the essence of vaccination.  One endures the unpleasantness and (finite) risk of prevention in order to stave off a catastrophe.  It’s a biological insurance policy.  And side-by-side, here’s a brilliant illustration of the relative risks: These are drawings from 1803 of a smallpox innoculation and a cowpox innoculation.  The pictures start on Day 2 and end on Day 14.  Which side would you rather be on?  If a picture says a thousand words, well, I’ve said enough.

                                    Smallpox                                                        Cowpox