I looked at 5 different websites about Vaxigrip. Three of the websites specifically cautioned people against taking Vaxigrip if they had a known "sensitivity" to thimerosal. One website listed formaldehyde and traces of Neomycin as ingredients. The Aventis Pasteur website also warned against allergy to formaldehyde, Neomycin and Ocotxinol 9.

Perhaps thimerosal is used in the formulation process and there are "traces" of it in the end product. I can't tell for sure.

Instead of risking a possible reaction to thimerosal, or at least having formaldehyde injected into your bloodstream, I would personally recommend taking supplements that strengthen your immune system, like:

Vitamin C
Elderberry Defense
Seasonal Defense

This way, you're naturally helping your body's own defense mechanisms. Besides, according to statistics I've heard concerning the 2004 (?) flu season, 97% of those that contracted the flu had actually received the flu shot.