I've had a flu shot every season now for years. It's my understanding that its effectiveness depends on how close the manufacturers come to predicting what's going to be the dominant virus(es) that season. Sometimes their prediction is good, sometimes less so. I recognize that some people have adverse reactions to the flu shot. Speaking for myself, I do not, and I also have not had the flu in all those years. Nasty intestinal viruses, yes, but not the flu. Also, as far as thimerosal goes, here's what the CDC has to say about it: "The majority of influenza vaccines distributed in the United States currently [do] contain thimerosal as a preservative. However, some contain only trace amounts of thimerosal and are considered by the Food and Drug Administration (FDA) to be preservative-free. Manufacturers of preservative-free flu vaccine use thimerosal early in the manufacturing process. The thimerosal gets diluted as the vaccine goes through the steps in processing. By the end of the manufacturing process there is not enough thimerosal left in the vaccine to act as a preservative and the vaccine is labeled 'preservative-free'.
" And manufacturers are starting to move away from using thimerosal at all in the production of the flu vaccine. It won't happen overnight, but it's already started. - Paula.