Abstract
A 61-year-old man presented with a 7-day history of watery diarrhea and loss of appetite after receiving the second dose of the Pfizer-BioNTech COVID-19 vaccine. Laboratory studies showed significant eosinophilia and an elevated IgE level (white cell count, 18.4×10(9)/L; eosinophil count, 9.5×10(9)/L; and IgE level, 540 IU/L). Symptoms resolved 10 days after vaccination without any steroids or antiallergic medications, and the eosinophil count had also returned to within normal limits 2 months later. Several cases of eosinophilic disorders following receipt of any type of injectable COVID-19 vaccine have been reported, so the etiology should be examined.