Multi-system inflammatory syndrome; This spontaneous case was reported by a consumer and describes the occurrence of MULTISYSTEM INFLAMMATORY SYNDROME (Multi-system inflammatory syndrome) in a 74-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 011A21A and 032L20A) for COVID-19 vaccination.     No Medical History information was reported.   On 22-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 27-Feb-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 27-Feb-2021, the patient experienced MULTISYSTEM INFLAMMATORY SYNDROME (Multi-system inflammatory syndrome) (seriousness criterion medically significant). The patient was treated with PREDNISONE for Adverse event, at an unspecified dose and frequency. At the time of the report, MULTISYSTEM INFLAMMATORY SYNDROME (Multi-system inflammatory syndrome) outcome was unknown.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   Prednisone which he had on and off for 6 months. Concomitant medication were not reported.  The patient did not experience any symptoms with the first dose of the vaccine. Within hours after the second dose he had swelling in the injection site on the left arm. The patient's swelling increased to the size of a golf ball, hard ball, and then soft ball. This swelling then spread down entire left arm and by the end of second day his hand was swollen. The patient could not recognize his own knuckles, and could not grasp a cup. The swollen areas were also very hot, but not red. This then went across his shoulders into his right arm , wrist, and hand. The patient watch was next to impossible to put on. By the 3rd day he was swollen from his neck to the bottom of his feet. The patient was hunched over, and could not move, and could not straighten up. The patient also had lower back pain, and it was extremely difficult to walk. The patient then went to his doctor on 4-5 days after who stated he was "part of the 1 percent," and diagnosed him with Multi-system inflammatory syndrome, explaining the second shot was attacked by the first shot.  Company comment: This case concerns a 74-year-old, male patient with no medical history reported, who experienced the unexpected event of multisystem inflammatory syndrome. The event occurred on the same day after the second dose of mRNA-1273. As reported, within hours after the second dose patient had swelling in the injection site on the left arm. The patient's swelling increased to the size of a golf ball, hard ball, and then soft ball. This swelling then spread down entire left arm and by the end of second day his hand was swollen. By the 3rd day patient was swollen from his neck to the bottom of his feet and went to his doctor 4-5 days after vaccination, who diagnosed him with Multi-system inflammatory syndrome. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This case concerns a 74-year-old, male patient with no medical history reported, who experienced the unexpected event of multisystem inflammatory syndrome. The event occurred on the same day after the second dose of mRNA-1273. As reported, within hours after the second dose patient had swelling in the injection site on the left arm. The patient's swelling increased to the size of a golf ball, hard ball, and then soft ball. This swelling then spread down entire left arm and by the end of second day his hand was swollen. By the 3rd day patient was swollen from his neck to the bottom of his feet and went to his doctor 4-5 days after vaccination, who diagnosed him with Multi-system inflammatory syndrome. The benefit-risk relationship of mRNA-1273 is not affected by this report.