Iodine may very well be a "trigger", however the immune response will only be as good/strong as it can be given immune supporting nutrition in the individual. This in and of itself could be problematic for some/many, rapidly, and further depleting scant resources. It could also be one of many issues behind some people not tolerating high doses...
Many minerals are deficient, and required for a strong immune system. In the presence of heavy metal toxicities, magnesium is always low, as absorption and utilization are both compromised... other minerals face the same dilemma.
I suspect that the "complimentary" supplement list to Iodine supplementation will get longer as time goes on.