It’s possible if they do the gold standard trials in a long term comparative study. But they’ll never do that lmao. The best thing we have is just to compare vaccinated and unvaccinated individuals but good luck find unvaxxed people. The only study I managed to find was one within a Jewish community that did not vaccinated their children. They found that the rate of allergies was nearly 0 in that group. There was like a 90% increased risk for developing allergies in vaxxed kids.