Myocarditis; cannot do strenuous work or exercise for a month; This spontaneous case was reported by a consumer and describes the occurrence of MYOCARDITIS (Myocarditis) in a 24-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 022C21A and 022C21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.   On 31-Aug-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 01-Oct-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 05-Oct-2021,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced MYOCARDITIS (Myocarditis) (seriousness criteria hospitalization and medically significant). In October 2021, the patient experienced IMPAIRED WORK ABILITY (cannot do strenuous work or exercise for a month). The patient was hospitalized from sometime in October 2021 to sometime in October 2021 due to MYOCARDITIS. At the time of the report, MYOCARDITIS (Myocarditis) was resolving and IMPAIRED WORK ABILITY (cannot do strenuous work or exercise for a month) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In October 2021, Electrocardiogram: normal (normal) EKG looked normal. In October 2021, Troponin: high (High) High troponin levels.         No concomitant medications were provided.  Patient had no prior history for the symptoms nor a history of COVID-19 infection. He had no medical or family history for myocarditis/pericarditis.  Patient experienced strong chest pain in the morning. He would rate the pain about 7 out of 10; 10 being the strongest pain. Walking or stretching would not make it better or worse. It was a constant stable pain. It was quite noticeable. The pain lasted 2-3 hours. The symptoms started on 05 Oct 2021 from 7 AM to 10:30 AM. The symptoms repeated everyday. On 06 Oct 2021, at about 9 AM to10:30 AM, the pain was less than on 05 Oct 2021. On 07 Oct 2021, it was less noticeable, but he could still feel the pain. Patient was kept under observation for a day and then they discharged him. He felt better and he did not have any symptoms now. He could not do strenuous work or exercise for a month. The hospital summary suspected the second dose of Moderna COVID-19 vaccine as the cause.  Patient received an injection in his belly that made his blood flow better. He was given a blood thinner injection. He reported that the hospital told him he could take Tylenol but he never did.  Company Comment : This case concerns a 24-year-old male patient with no relevant medical history, who experienced the serious expected event of Myocarditis. The event occurred approximately 5 days after the Moderna COVID-19 Vaccine. The patient had high troponin levels and EKG was normal. The patient was under observation for a day then got discharged. The rechallenge was not applicable as the event occurred after the second dose. The patient received the second dose approximately a month after the first dose. The benefit-risk relationship of COVID-19 Vaccine is not affected by this report.; Sender's Comments: This case concerns a 24-year-old male patient with no relevant medical history, who experienced the serious expected event of Myocarditis. The event occurred approximately 5 days after the Moderna COVID-19 Vaccine. The patient had high troponin levels and EKG was normal. The patient was under observation for a day then got discharged. The rechallenge was not applicable as the event occurred after the second dose. The patient received the second dose approximately a month after the first dose. The benefit-risk relationship of COVID-19 Vaccine is not affected by this report.