cellulitis; 50 cent sized red raised skin on left calf; lethargic; foot is extremely swollen; pain; difficulty breathing/short of breath/panting; Rash became very hot; swelling; weak; allergic reaction; painful to touch/Rash; Chills; throwing up through out all this; 3 hors temp of 104 F; This spontaneous case was reported by a consumer and describes the occurrence of CELLULITIS (cellulitis) in a 55-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. unknown) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Diabetes.   On 23-Aug-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On an unknown date, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced CELLULITIS (cellulitis) (seriousness criterion medically significant), RASH ERYTHEMATOUS (50 cent sized red raised skin on left calf), LETHARGY (lethargic), PERIPHERAL SWELLING (foot is extremely swollen), PAIN (pain), DYSPNOEA (difficulty breathing/short of breath/panting), MILIARIA (Rash became very hot), SWELLING (swelling), ASTHENIA (weak), HYPERSENSITIVITY (allergic reaction), RASH (painful to touch/Rash), CHILLS (Chills), VOMITING (throwing up through out all this) and PYREXIA (3 hors temp of 104 F). The patient was treated with DIPHENHYDRAMINE HYDROCHLORIDE (BENADRYL [DIPHENHYDRAMINE HYDROCHLORIDE]) at an unspecified dose and frequency. At the time of the report, CELLULITIS (cellulitis), RASH ERYTHEMATOUS (50 cent sized red raised skin on left calf), LETHARGY (lethargic), PERIPHERAL SWELLING (foot is extremely swollen), PAIN (pain), DYSPNOEA (difficulty breathing/short of breath/panting), MILIARIA (Rash became very hot), SWELLING (swelling), ASTHENIA (weak), HYPERSENSITIVITY (allergic reaction), RASH (painful to touch/Rash), CHILLS (Chills), VOMITING (throwing up through out all this) and PYREXIA (3 hors temp of 104 F) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Body temperature: 104 (High) 104F 103.2F 102.9F. On an unknown date, Computerised tomogram: cellulitis (abnormal) Cellulitis.         Concomitant medications was not reported. Treatment history included IV antibiotics, antihistamine and topical cream. Patient blood group reported as O.  50 cent sized red raised skin on left calf (7 inch from knee and 4 inches above ankle). 6 hours later rash spread to 4 inch wide band around calf. The patient did a CT and thinks it looks like cellulitis then transported him to ER at hospital and they at the hospital he was treated with IV antibiotic. The patient has blood type O and diabetic, who maintained low blood glucose by diet and exercise. Doctors are waving off that it might be an allergic reaction  Company comment: This case concerns a 55 Y/O M with serious unexpected cellulitis, and non-serious rash erythematous, lethargy, peripheral swelling, pain, dyspnoea, miliaria, swelling, asthenia, hypersensitivity, rash, pyrexia, chills, vomiting. Latency unknown after second dose. Outcomes unknown. Rechallenge not applicable. Reporter causality not provided. Diabetes confounder. Causal relationship possible based on temporal association. The benefit-risk relationship of mRNA-1273 is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 09-Sep-2021: Follow up received contains Patient details,Medical history, Lab data, Suspect drug details, New events cellulitis, swelling, pain, foot is extremely swollen,difficulty breathing, vomiting,  weak,Heat rash case updated to serious, Treatment history; Sender's Comments: This case concerns a 55 Y/O M with serious unexpected cellulitis, and non-serious rash erythematous, lethargy, peripheral swelling, pain, dyspnoea, miliaria, swelling, asthenia, hypersensitivity, rash, pyrexia, chills, vomiting. Latency unknown after second dose. Outcomes unknown. Rechallenge not applicable. Reporter causality not provided. Diabetes confounder. Causal relationship possible based on temporal association. The benefit-risk relationship of mRNA-1273 is not affected by this report.