You keep sayings his like there is some rather large contingent of the population unable to safely be vaccinated. Diseases were able to be eradicated because that is such a small group of people.
That is why until recently, measles were eradicated in the U.S. Because the majority of the population either had an immunity from having or being exposed or the MMR vaccination. Same reason for polio. A thoroughly vaccinated population.
However, because of the anti-vaccination movement, fortunately a very small movement, measles is back. All it takes is one unvaccinated individual - and in the case of the Disneyland outbreak, someone as the CDC suspects from a foreign country with little or no vaccination programs - contagious but not exhibiting the classic symptom, the rash, for the disease to spread. People have talked about the "herd" concept - you ensure the majority of the herd is vaccinated and thereby protect those members of the herd who are unable to be vaccinated. However, this doesn't take into count unvaccinated outsiders who enter the Herd's territory.
And all it took for this anti-vaccination movement to gain credibility was for one celebrity, after reading or hearing about a flawed and falsified study in the British medical journal, to loudly and repeatedly blame the MMR shot for her child's autism. And in spite of the study being retracted and the medical community repeatedly stating the study was flawed and the date falsified and the doctor conducting the study having his license to practice medicine revoked as a result, there are still parents who think the MMR shot causes autism. I recently read an article on the anti-vaccination movement. The most sobering party of the article? That in spite of anti-vaccination parents being provided empirical evidence that vaccinations don't cause autism, they still believe it. "You can take a horse to water but you can't make him drink."
When the state health department, after the outbreak starting at Disney, looked at the unvaccinated population in Southern California, they found the more affluent areas of LA and Orange counties had a higher rate of unvaccinated school aged children than they would have thought. Most folks would have assumed the opposite, mainly because of problems with access to health care poorer communities faced.