The use of vaccines is a public health necessity; vaccines are by far the most cost effective tool we have for preventing the spread of communicable diseases.
There have always been controversies about vaccines: there is non-zero risk to individuals from any medical treatment, and significant benefit to the population as a whole. As a single individual, you remove the (very small) risk by not having the vaccine, and you gain most all of the benefits if most everyone else around you has been vaccinated.
Spreading fear and misinformation about the safety of vaccines can cause direct, measurable and irreversible harm. Measuring the connection between a medical treatment and possible harmful effects is something drug companies can do very well, and the FDA approvals process (when it works) keeps the companies honest. We have solid, irrefutable and repeatable scientific evidence that shows vaccines do not cause these diseases, like autism.
The best article covering this was in the Bad Astronomy blog from Discover, aptly titled Antivax Kills.