We can be reassured that vaccine-associated anaphylaxis has been a rare event, at one case per million injections, for most known vaccines.6 Acute allergic reactions after vaccination might be caused by the vaccine antigen, residual nonhuman protein, or preservatives and stabilizers in the vaccine formulation, also known as excipients.6 Although local reactions may be commonly associated with the active antigen in the vaccine, IgE-mediated reactions or anaphylaxis have historically been more typically associated with the inactive components or products of the vaccine manufacturing process, such as egg, gelatin, or latex.6