Mercury Content of Vaccines in the USA
Mercury was phased out of most US vaccines between 1999 and 2002. The multi-dose flu vaccines, one brand of tetanus toxoid, and one brand of meningococcal vaccine still have 25 micrograms of mercury per shot in the multi-dose vials. To be safe, I would always refuse multi-dose flu shots and insist that your flu shot (if you are getting one) be single dose thimerosal-free. When boosting for tetanus, just use the Tdap and avoid the tetanus toxoid, and for meningococcal protection avoid the multi-dose Menomune vaccine made by Sanofi Pasteur. The Menactra from Sanofi Pasteur is fine.
For a comprehensive table of vaccines and their mercury content, click here.