This spontaneous case was reported by a consumer and describes the occurrence of AUTOIMMUNE DISORDER (Caller states the Severe Autoimmune Reaction) in an elderly male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 036A21A and 012M20A) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below. No Medical History information was reported. On 06-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 06-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. In March 2021, the patient experienced AUTOIMMUNE DISORDER (Caller states the Severe Autoimmune Reaction) (seriousness criterion medically significant), PERIPHERAL SWELLING (Fingers swell up the size of sausages) and FEELING ABNORMAL (when he sits it feels as if his buttocks has no flesh or padding as if he is sitting on bone). The patient was treated with PREDNISONE at a dose of 5 milligram once a day; PREDNISONE at a dose of 2.5 milligram once a day and HYDROXYCHLOROQUINE at a dose of 200 milligram once a day. At the time of the report, AUTOIMMUNE DISORDER (Caller states the Severe Autoimmune Reaction), PERIPHERAL SWELLING (Fingers swell up the size of sausages) and FEELING ABNORMAL (when he sits it feels as if his buttocks has no flesh or padding as if he is sitting on bone) had not resolved. No concomitant medications were reported. Patient stated that he experienced severe autoimmune reaction couple of weeks after his second shot. Reporter describes the reaction as his fingers swell up the size of sausages, when he sits it feels as if his buttocks has no flesh or padding as if he was sitting on bone, and when he was going up or down the stairs it was excruciating. This case was identified as part of a retrospective clean-up activity where certain emails received in the Moderna mailbox were missed to be booked-in. Company Comment: This spontaneous case concerns an elderly, male patient with no medical history reported, who experienced the unexpected, serious (medically significant) event of autoimmune disorder and other unexpected, non-serious events. The events occurred unknown number of days after receiving the second dose of the mRNA-1273 vaccine. Of note, the event onset dates were reported as unspecified dates in Mar2021, hence, the onset latency could not be assessed. The second dose was given 28 days after the first dose of the mRNA-1273 vaccine. It was reported that the patient experienced a severe autoimmune reaction a couple of weeks after receiving the second dose. His fingers got swollen up to the size of sausages. When he seated, it felt as if his buttocks have no flesh or padding as if he sat on bone, and climbing the stairs was excruciating. As per the patient's doctor, the vaccine caused a severe autoimmune disorder. However, no details were reported regarding diagnostic test/s and specific diagnosis. The patient was treated with prednisone 5 mg once daily (unspecified duration) which was tapered to 2.5 mg once daily and hydroxychloroquine 200 mg once daily (unspecified duration). The events had not resolved at the time of the report. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report. Sender's Comments: This spontaneous case concerns an elderly, male patient with no medical history reported, who experienced the unexpected, serious (medically significant) event of autoimmune disorder and other unexpected, non-serious events. The events occurred unknown number of days after receiving the second dose of the mRNA-1273 vaccine. Of note, the event onset dates were reported as unspecified dates in Mar2021, hence, the onset latency could not be assessed. The second dose was given 28 days after the first dose of the mRNA-1273 vaccine. It was reported that the patient experienced a severe autoimmune reaction a couple of weeks after receiving the second dose. His fingers got swollen up to the size of sausages. When he seated, it felt as if his buttocks have no flesh or padding as if he sat on bone, and climbing the stairs was excruciating. As per the patient's doctor, the vaccine caused a severe autoimmune disorder. However, no details were reported regarding diagnostic test/s and specific diagnosis. The patient was treated with prednisone 5 mg once daily (unspecified duration) which was tapered to 2.5 mg once daily and hydroxychloroquine 200 mg once daily (unspecified duration). The events had not resolved at the time of the report. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report.