ProPublica: “Two Stanford University researchers wondered how many people would suffer if vaccination rates dropped or shots became entirely unavailable for four of the most infamous diseases: polio, measles, rubella and diphtheria…”“Their model shows that at current vaccination rates, the nation is already teetering on the brink of an explosion in measles cases — one that would be virtually wiped out with just a 5% increase in vaccination. But if current rates drop by half, all four diseases could return.”