CSF3 and hemophagocytic syndrome: We suspected that HLH was associated with Comirnaty®based on the HLH-2004 diagnostic criteria (fulfilling four out of the eight criteria).[8] On the second day of admission, pulsed intravenous (IV) methylprednisolone (500 mg/day for 3 consecutive days) and granulocyte-colony stimulating factor was started, followed by oral prednisolone (30 mg once daily).