Glad you're enjoying it. That 1721 smallpox outbreak in Boston was a key moment in the history of immunisation. Pity Onesimus wasn't around to see it. I'll leave the military historians to debate whether there would be a USA without the immunisation that Onesimus introduced!

Yes, the full credit always goes to Jenner who "pioneered the concept."

In fairness, Jenner did bring in the first vaccine. Using cowpox to induce immunity to smallpox was fundamentally different to deliberately infecting children with smallpox. Though it was Pasteur who really established vaccination as we understand it today.