Different "organic" certifying agencies have different rules. You can always check with your local one to see what theirs are.
I'd suggest calling you county extension agency office to discuss vaccinations relative to your area and expecially how you plan to manage your chickens. Vaccination requirements should be different if you plan to show your chickens, bring in new chickens from chicken swaps or other outside flocks, or keep a closed flock. Hopefully your extension office will put you in touch with someone who actually knows chickens.
One specific vaccination makes your birds carriers for the rest of their lives. Once you vaccinate for that, you have to vaccinate all your new chickens. Any chickens yours come in contact with will be infected so you can't responsibly give them away or take them to chicken swaps. I'm too lazy this morning to look that one up and I cannot remember which one it is, but I wanted to mention that.
Certain vaccinations, such as the one for Cocci, requires certain treatment for a time after the vaccination or you negate the beneficial effects of the vaccination.
After I spoke with an Ag professor with U of Arkansas who raises and used to show chickens that the local extension office lined me up with and explaining how I planned to manage them, the recommendation was to not vaccinate for anything. If my location or management practices were different, the recommendation could well have been different.
Good luck!!!
