It looks likes one of the batches of flu vaccine was re-called in Canada due to a higher than normal rate of adverse reactions.
http://ca.news.yahoo.com/s/reuters/0..._us_flu_canada
Fortunately, the people recovered.. but it serves as an example of why it pays to be cautious. If they can't foresee the short term risks, then what do they know about the long term risks of a bad batch of vaccine?