"When the smallpox vaccine was developed, did they need a control group?" --- Yes they should have required an actual scientific vaccine study, long-term too, that would also account for variables, that's what science is, removing the variables and testing theories, proving/unproving.
But to just produce a vaccine to give it out without that proper testing, then no, that isn't science. To vaccinate everyone is eugenics. So what happened when they gave out smallpox vaccine to everyone without proper testing, that is why smallpox is looked down on, because people worship it without any actual proof that it did anything that it was claimed to have done.
How on earth could you see inside the body to physiologically know without any doubt, that the small pox vaccine "worked"? Because people not dying after a vaccination, doesn't mean the vaccine was to be bragged about as the one thing that made them "healthier". I could easily say that the natural immune system fought off the stupid vaccine-bullshit, that they weren't in any harms way of smallpox, because the natural immune system would have fought it off.
"In the United States smallpox is not a public health danger anymore like it used to be. Why? Because of the vaccine." --- Again, false assumption. There's no physiological proof in existence, then or now, that the vaccine stopped smallpox. Smallpox was on its way out from sanitation standards. Remember at the same time, there were doctors that were against washing-hands before a surgery with another patient.
Literally a whole swath of so-called "scientists" that were against washing hands before surgery.
Are the same so-called "scientists" that swear-off vitamins(which your body uses), in order to push vaccines that have no physiological proof of any claimed benefits.