He was diagnosed with infection of arm, or cellulitis; swelling of knuckles and hand; swelling of knuckles and hand/swelling of injection site to elbow and forearm; malaise; fever of 100-102 F; swelling of injection site to elbow and forearm; swelling underneath armpit; soreness; This spontaneous case was reported by a consumer and describes the occurrence of CELLULITIS (He was diagnosed with infection of arm, or cellulitis), PERIPHERAL SWELLING (swelling of knuckles and hand), JOINT SWELLING (swelling of knuckles and hand/swelling of injection site to elbow and forearm), MALAISE (malaise), PYREXIA (fever of 100-102 F), INJECTION SITE SWELLING (swelling of injection site to elbow and forearm), LYMPHADENOPATHY (swelling underneath armpit) and MYALGIA (soreness) in a 71-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.     No Medical History information was reported.    On 08-Dec-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced CELLULITIS (He was diagnosed with infection of arm, or cellulitis) (seriousness criteria hospitalization and medically significant), PERIPHERAL SWELLING (swelling of knuckles and hand) (seriousness criterion hospitalization), JOINT SWELLING (swelling of knuckles and hand/swelling of injection site to elbow and forearm) (seriousness criterion hospitalization), MALAISE (malaise) (seriousness criterion hospitalization), PYREXIA (fever of 100-102 F) (seriousness criterion hospitalization), INJECTION SITE SWELLING (swelling of injection site to elbow and forearm) (seriousness criterion hospitalization), LYMPHADENOPATHY (swelling underneath armpit) (seriousness criterion hospitalization) and MYALGIA (soreness) (seriousness criterion hospitalization). The patient was hospitalized from 11-Dec-2021 to 14-Dec-2021 due to CELLULITIS, INJECTION SITE SWELLING, JOINT SWELLING, LYMPHADENOPATHY, MALAISE, MYALGIA, PERIPHERAL SWELLING and PYREXIA. The patient was treated with VANCOMYCIN (intravenous) for Cellulitis, at a dose of IV vancomycin until Tuesday and CEFALEXIN MONOHYDRATE (KEFLEX [CEFALEXIN MONOHYDRATE]) for Cellulitis, at a dose of 4 days of Keflex upon discharge. At the time of the report, CELLULITIS (He was diagnosed with infection of arm, or cellulitis), JOINT SWELLING (swelling of knuckles and hand/swelling of injection site to elbow and forearm), MALAISE (malaise), PYREXIA (fever of 100-102 F), INJECTION SITE SWELLING (swelling of injection site to elbow and forearm), LYMPHADENOPATHY (swelling underneath armpit) and MYALGIA (soreness) outcome was unknown and PERIPHERAL SWELLING (swelling of knuckles and hand) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 11-Dec-2021, Body temperature: 102 (abnormal) Patient still had a fever of 102. On an unknown date, Body temperature: 100-102 (abnormal) fever of 100-102 F.         No concomitant medication details was reported.  Patient visited his HCP on 21Dec2021, his doctor is going to check his blood counts to make sure Keflex is the proper antibiotic to take.  Company Comment: This case concerns a 71-year-old male patient, with no reported medical history, who experienced the unexpected serious events of Cellulitis, Peripheral swelling, Joint swelling, Malaise, Injection site swelling, Lymphadenopathy, Myalgia and Pyrexia. The events occurred on an unknown date after the third dose of mRNA-1273 Vaccine which resulted in hospitalization. The patient was given intravenous Vancomycin and Keflex as treatment.  At the time of the report the outcome of the events was Unknown. The rechallenge is not applicable since no further dosing is expected. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.; Sender's Comments: This case concerns a 71-year-old male patient, with no reported medical history, who experienced the unexpected serious events of Cellulitis, Peripheral swelling, Joint swelling, Malaise, Injection site swelling, Lymphadenopathy, Myalgia and Pyrexia. The events occurred on an unknown date after the third dose of mRNA-1273 Vaccine which resulted in hospitalization. The patient was given intravenous Vancomycin and Keflex as treatment.  At the time of the report the outcome of the events was Unknown. The rechallenge is not applicable since no further dosing is expected. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.