Humans have existed for hundreds of thousands of years with no vaccines. Let's not be needlessly fearmongering when it comes to their necessity.

In this day and age, given the quality of medical treatment available to most of the population, any outbreak of diseases can be handled in a much better way, and with less comparative casualties than ever before, regardless of the use o vaccines.

Vaccines are useful, there is no doubt about that, but they are in no way a necessity without which we cannot live.