Fortunately, I haven't had a bout of Flu in a number of years. There was a time or two, if I remember correctly, where despite the shot, I got the flu.
I must be honest and admit, I never really looked into the issue of what is actually in a flu shot. As for mercury, I know it has been a source of concern with fever thermometers, as I became aware after two occasions where having my temperature taken, one time by mouth, and a few years later rectally, the thermometers broke! I did not suffer any problems though.
I will certainly look up information on these preservatives as applied to the flu shots. Thanks.