Therefore, the authors speculated that the vaccine–material immune complexes (e.g., PEG immune complexes) may be more likely to exist in the blood than in the skin and that anaphylaxis reactions may mostly occur due to a non-IgE mediated pathway (i.e., via complement activation through plasma immune complexes with the materials), according to the negative result of the administered SPTs (Figure 1g) [43]. Here, IGHE is linked to anaphylaxis.