Yup. The development the first reliable, commercially-released vaccine took over 20 years and in all that time there were a few millions of human trials, never mind what other countries (who, imagine this, were secretive about their experimentation) did.
Salk's (commercially released 1955) vaccine "only" had about 3 years of organized testing on humans, but it also followed 20+ years of other research. And in his vaccine, there were large number of people who died, I think in the six figures (largely due to a lab screwing up the serum). Sabin's (1961) ended up being the baseline which has lasted in an only-slightly modified form up to the present day.
Of course it's ludicrous to in almost any way compare modern vaccine development to these early achievements - medicine was comparatively primitive back then, and all that time and millions of inoculations were needed to get to a reasonable solution. And, it's important to understand that the entire science of vaccines now has advanced such that what seems safe "only" after 10-15 years of development is becoming obsolete - clinical trials etc. are beginning to rapidly speed up the time to a fraction of the original polio window.
Nevertheless the polio vaccine was a remarkable achievement - yeah, it killed a lot more people on the way, but given the knowledge at the time, it was about the best one could hope for. Today however it would be almost criminally reckless to use those methods.
All that said and done, there's still risk and this vaccine was developed more quickly than would be the ideal - and there are risks. I wouldn't want to do most vaccines at this speed, but at least it's nice to know they can at times pull it off if they have to, so it seems.