IGHE and Allergy: Although skin testing to vaccine and vaccine excipients (in the case of COVID-vaccines) seems to lack precision, as the mechanism of adverse reactions in most cases is less likely to be IgE-mediated or the quantity of PEG/PS80 in the vaccines is very low and therefore subthreshold to provoke a reaction, the other side of the coin is a reported sensitivity of 95.8% regarding skin tests in patients with suspected PEG allergy in a large review [6, 20, 21].