Weighing Vaccine Risk vs Benefit

Picture the statue of Justice, a blindfolded woman with a scale in her hand presumably weighing the evidence for guilt on one side versus for innocence on the other. The FDA and CDC have a similar task when they consider approving new vaccines, as they weigh the potential population benefit versus side effects and risks. One is willing to put up with more risk and side effects (when a safer drug is not available) when treating a life threatening illness such as a cancer. Vaccines, being given to generally healthy individuals, are held to a higher safety standard and more stringent side effect profile.  

Very effective vaccines, with even a mild-to-moderate safety/adverse effect profile, will often not be approved or be subsequently withdrawn, partly as a result of the desire to maintain public confidence in the vaccination system. 

Here's a short test (1 question) of your memory of controversy that may, or may not, have surrounded some late 20th- and an an early 21st-century vaccine approvals.