Influenza Vaccination-associated Acute Thrombocytopenia and Diffuse Alveolar Hemorrhage

Influenza vaccination can trigger various adverse reactions, and thrombocytopenia is also rarely reported. Although patients with mild thrombocytopenia are sometimes asymptomatic, severe thrombocytopenia can cause severe bleeding. We herein report a rare case of severe thrombocytopenia that occurred within one day of influenza vaccination and diffuse alveolar hemorrhage (DAH) leading to acute respiratory failure. The patient was treated with glucocorticoid pulse therapy, intravenous immunoglobulin, and temporary mechanical ventilation, and eventually he made a full recovery. Vaccine-related thrombocytopenia and DAH should be considered adverse reactions, even if they develop very soon after vaccination.