By "at risk of a relatively common complication", I'm not trying to say that the vaccines contain any known allergens. I'm not enough of an expert to know if th

By "at risk of a relatively common complication", I'm not trying to say that the vaccines contain any known allergens. I'm not enough of an expert to know if those specific ones do or don't. I'm just saying that people with severe allergies often have allergic reactions to vaccines.