While one group (arguably the large majority) sees vaccination or inoculation as an effective, safe and historically life-saving procedure - another (smaller) group simply doesn’t.  Whereas some emphasize large-scale effectiveness and safety trials, others highlight their connections to pharmaceutical companies and design biases. While some argue that vaccines were responsible for eradicating disease, others point to contrasting historical analyses that suggest diseases were sharply reduced long before vaccines were introduced (for other reasons - hygiene, etc.) - rather than how the history is usually characterized (with vaccination simultaneous with decreasing infectious disease, and thus “taking all the credit”).  

On many levels, the differences in perspective are vast - if little understood across the divide.  When combining the shared passion for children with very little tolerance for disagreement on either side, these factors create what might well be the most difficult conversation in America.