A 22-year-old healthy male with no medication use received the Pfizer-BioNTech BNT16B2b2 mRNA vaccine through his work as an emergency department employee. On day three, post-vaccination, he experienced widespread petechiae (Figure 1) and gum bleeding, which prompted his presentation. He was current on his vaccines, including yearly influenza, with no history of adverse reactions. He denied respiratory and gastrointestinal complaints or a history of infection.He had no personal or family history of bleeding or autoimmune disease. Vital signs and the remainder of his exam were normal. Laboratory tests revealed normal white-cell count, hemoglobin, and severe thrombocytopenia with a platelet count of 2 × 10 9 /L. Two months prior to receiving the vaccine, the patient was evaluated at an outpatient clinic for upper respiratory symptoms. His PCR assay returned negative for SARS-CoV-2, and complete blood count was unremarkable with a normal platelet count of 145 × 10 9 /L (reference range, 140-400 × 10 9 /L). The upper respiratory symptoms resolved within a few days, and the patient had no further complaints. However, as a precautionary measure, one-week post outpatient evaluation, he was again tested for SARS-CoV-2, which returned negative.At the emergency department on day 3, post-vaccination, the following labs were normal or negative: prothrombin time, partial thromboplastin time, fibrinogen, BUN, creatine, electrolytes, bilirubin, LDH, alkaline phosphatase, albumin, globulin, total protein, and haptoglobin. The aspartate aminotransferase (42) and alanine aminotransferase (90) were mildly elevated; however, they normalized the next day. Additionally, he tested negative for HIV, Hepatitis B, Hepatitis C antibody, and Epstein-Barr Virus serology. A nasopharyngeal swab also returned negative for SARS-CoV-2 antigen. The patient was then admitted and given dexamethasone 40 mg daily for 4 days, a platelet transfusion, and intravenous immunoglobulin at