They didn’t have a way to refrigerate it, so they took a bunch of orphans and gave it to them and then used their blood to give it to the next person and that’s how they got it from europe to the americas
THE FIRST EVER VACCINE WAS INTRODUCED IN 1796 BY SOMEONE NAMED EDWARD JENNER. IT WAS A RUDIMENTARY VERSION OF THE COWPOX VIRUS USED TO ELIMINATE SMALLPOX