My company offers them free to employees. I have had them many times. The only time I had any side effects was from a blown stick. The nurse stuck me too high and the serum went into the shoulder joint, causing me about a week of severe achiness in that shoulder. I haven't seen anyone in our company come down with any serious side effects from the shot in the last several years. We haven't been hit too hard by the flu either.

Locking your doors doesn't always prevent burglary, but I lock mine just the same.