I can't imagine the Iodine impacting the effectiveness of the vaccine.....I won't pretend I am an expert on that either but it doesn't make sense to me.
You should take a bunch of Iodine with you on this trip though, both for internal and external use.
you might see if it is possible to get any of the upcoming V's that are thimerosol free.....it is a mercury based preservative, you really don't want any of that in you.
Iodine has been shown to help mobilize heavy metals out of you, so it can be helpful for that, however when you get back you may want to get a hairtest to check for heavy metals and use Andy Cutler's counting rules to evaluate the test, just to be sure you haven't dosed yourself with these vaccines. Effective measures using chelating agents can be used if necessary to remove heavy metals.
Funny you should mention HC. I have been taking 15mg for years....7 years I think. I am just starting to wean myself off now after one year on Iodine...I tried a couple of times before and it didn't work. I am just into my second week and taking 10mg. Last week was fine at 12.5mg. I wouldn't necessarily be in a hurry to get off of it unless you really feel great and ready.
I know you are trying to do the supplement thing naturally but I am going to harp you again to get some good quality B-vitamins --complex and extra B2/3 and ascorbic acid
B vitamins and vitamin C are hugely important for the adrenals and for healing the possible Iodine transport issue. Please don't skimp on these important nutrients
Linus Pauling took about 10g of ascorbic acid a day and he lived until 93 and he was healthy and strong still..... but unfortunately he was hit by a bus.....