i absolutely cannot take vaccinations, at least the usual flu ones. For years I could take the Flu vaccination if it was without mercury, but this year, at my son's urging, I sought out a pediatrician who would give the flu vaccination without mercury. I got sick anyway, and looking at the various toxins which crowd into various brands of flu vaccine, I can see why.
But GirlfromNorway, I may be a special case (or maybe not). I have Porphyria as well as having an earlier MS diagnosis, and people with Porphyria are more likely to have reactions to toxins such as these, because of difficulty in the detox pathway.
I remember having my first Polio vaccination and getting double vision for a few hours, which meant I could not go to my teaching job, but then this went away quickly.
The reaction to the flu shots is largely spasticity, stiffness and pain and incoordination--difficulty doing thing with my hands and feet, and difficulty thinking clearly, which puts me then into an emotional tizzy of frustration. I have not had the double vision with the flu shot that I had from the polio shot, but I recovered quicker from the polio shot. It takes me several days at least to get my bearings after a flu shot.
It has always seemed on the MS forums that some people react as I do to these things, and others do not. Which underscores to me that MS arrives and grows through different pathways...we are not all the same. Some of us have co-morbid diseases, some do not. Some have significant chemical sensitivity, others do not have so much, or even no apparent chemical sensitivity.

Needless to say, I suffered from doctor disbelief and brush-offs when young...throughout my whole youth. And was late in getting any diagnosis. First MS, later Porphyria. I now also have Polycythemia Vera, but that is not closely related to the neuro-impacting MS and Porphyria.