The odds of getting the disease if unvaccinated varies with the frequency and the depth of "herd immunity", the degree to which the rest of the community is vaccinated. The reason we have made vaccines for these diseases is because the chances of bad results with the real thing is much more than the consequences of vaccination. Measles encephalitis leaves the child with severe retardation, and is a not-that-rare outcome of having measles. Chicken pox can result in male sterilization, and the mumps are not a benign illness, either. And polio is a terrific disease, causing paralysis and stunting of limbs, not to mention the cases of paralysis of the breathing muscles necessitating the use of an iron lung to enable the patient to breathe. These now-preventable diseases have taken a huge toll in human life. It is a sad commentary that people fear the vaccine now more than they fear the disease. So much pain and suffering could be prevented.
