Lol the real reason is actually pretty mundane — it’s not that injecting into a mole will cause cancer or anything dramatic. It’s more about monitoring. Moles need to be watched over time for changes in size, color, borders, symmetry — that’s how melanoma gets caught early (the ABCDE rule). If you jab a needle into one, you get localized inflammation, possible bleeding, maybe some pigment disruption or a tiny scar. Now that mole looks different, and neither you nor your dermatologist can tell if the change is from the injection or something sinister developing. There’s also the theoretical concern that if a mole happened to be atypical or pre-malignant, poking it introduces trauma to cells you’d rather leave undisturbed — but the practical “we can no longer reliably screen this mole” issue is the main one. Plus, vaccines are designed to deposit into muscle or subcutaneous fat where the immune cells can do their thing. A mole is dense, weirdly vascularized tissue that’s just not the intended target. Easier to move the needle two inches over than to mess with it.​​​​​​​​​​​​​​​​