Flu Shots for Us? What is your advice regarding flu shots for people with CFIDS & FM – any criteria? Reply: This has to be evaluated carefully by your physician to make sure that it won’t make your condition worse by temporarily altering your immune system. And then there is the slight but real chance that the vaccine could be contaminated. Interestingly, a published study of commercial vaccines in the journal VACCINE found that about 6% were contaminated with bacteria, such as Mycoplasma species.