IgE is the antibody for allergies, it’s also the one we use for worms/parasites/big multi cellular disease organisms. I can see why intentional infection with parasitic worms can help with autoimmune/severe allergies, it’s an interesting subject of research.

Anyway, yeah, people definitely took the wrong lessons about natural immunity after acquiring a disease. The comparison to cartilage damage is really apt. Cause, yeah, sometimes it just makes everything worse if you get a disease. So like if you could avoid it by getting a shot, you think it’d be obvious to get the shot providing a person isn’t allergic to the ingredients or immunocompromised in the first place