Myasthenia gravis exacerbation; Myasthenia gravis crisis; acute hypercapnic respiratory failure; acute renal failure; This literature-non-study case was reported in a literature article and describes the occurrence of MYASTHENIA GRAVIS (Myasthenia gravis exacerbation), MYASTHENIA GRAVIS CRISIS (Myasthenia gravis crisis), RESPIRATORY FAILURE (acute hypercapnic respiratory failure) and ACUTE KIDNEY INJURY (acute renal failure) in a 77-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.    The patient's past medical history included Intubation (For acute hypercapnic respiratory failure the patient was intubated and transferred to the medical intensive care unit (MICU). Then successfully extubated.) and Mechanical ventilation since an unknown date. Concurrent medical conditions included Myasthenia gravis (The patient was first diagnosed with Myasthenia gravis five years ago and has been maintained on prednisone).   On an unknown date, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On an unknown date, the patient experienced MYASTHENIA GRAVIS (Myasthenia gravis exacerbation) (seriousness criteria hospitalization and medically significant), MYASTHENIA GRAVIS CRISIS (Myasthenia gravis crisis) (seriousness criteria hospitalization and medically significant), RESPIRATORY FAILURE (acute hypercapnic respiratory failure) (seriousness criterion hospitalization) and ACUTE KIDNEY INJURY (acute renal failure) (seriousness criterion hospitalization). The patient was treated with PREDNISONE for Myasthenia gravis, at a dose of 10 milligram; PREDNISONE for Myasthenia gravis, at a dose of 7.5 milligram once a day; PREDNISONE ongoing since an unknown date for Myasthenia gravis, at a dose of 7.5 milligram once a day; PREDNISONE for Myasthenia gravis, at a dose of 40 milligram; PYRIDOSTIGMINE ongoing since an unknown date for Myasthenia gravis, at a dose of 60 milligram every four hours; PYRIDOSTIGMINE for Myasthenia gravis, at a dose of 60 milligram every four hours; IMMUNOGLOBULINS NOS (intravenous) for Myasthenia gravis aggravated, at a dose of 2 dosage form and IMMUNOGLOBULINS NOS (intravenous) for Myasthenia gravis aggravated, at a dose of 35 gram once a day. At the time of the report, MYASTHENIA GRAVIS (Myasthenia gravis exacerbation) and MYASTHENIA GRAVIS CRISIS (Myasthenia gravis crisis) outcome was unknown, RESPIRATORY FAILURE (acute hypercapnic respiratory failure) was resolving and ACUTE KIDNEY INJURY (acute renal failure) had resolved. Related    DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood gases: acute hypercapnic respiratory failure An arterial blood gas analysis (ABG) confirmed acute hypercapnic respiratory failure. On an unknown date, Chest X-ray: normal (normal) Chest x-ray was negative for any infiltrates, effusions, or consolidations.. On an unknown date, Electrocardiogram: sinus tachycardia An electrocardiogram showed sinus tachycardia. On an unknown date, Heart rate: tachycardia In the ER, vitals were notable for tachycardia (110 beats per minute). On an unknown date, Laboratory test: significant Labs were significant for acute renal failure (due to poor oral intake).. On an unknown date, Oxygen saturation: hypoxia In the ER, vitals were notable for d hypoxia (Pox 91% on room air). On an unknown date, Respiratory rate: tachypnea In the ER, vitals were notable for tachypnea (20 breaths per minute). On an unknown date, SARS-CoV-2 test: negative (Negative) Negative. On an unknown date, Septic screen: negative (Negative) negative.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered MYASTHENIA GRAVIS (Myasthenia gravis exacerbation), MYASTHENIA GRAVIS CRISIS (Myasthenia gravis crisis), RESPIRATORY FAILURE (acute hypercapnic respiratory failure) and ACUTE KIDNEY INJURY (acute renal failure) to be related.    Patient presented to the emergency room (ER) with complaints of dysphagia for one week.  The dysphagia was associated with non-specific arthralgia, intermittent fevers, chills, and fatigue. The remaining review of systems is negative. Patient was compliant with medications.  In the ER, vitals were notable for tachypnea, tachycardia, and hypoxia  Patient received the first and second doses of Moderna COVID-19 vaccine approximately five and one weeks prior to presentation.  Patient was admitted to the neuro floor with MG exacerbation  Patient's acute renal failure resolved with adequate IV hydration.   Over the next few days, the patient's oxygen requirement normalized, but the dysphagia persisted. On day six of admission, he acutely decompensated with another crisis of MG manifested by lethargy and flaccidity.  Patient was started on prednisone 10 mg (which was gradually increased in 48-hour intervals to 40 mg), another two intravenous immunoglobulin were given on days 9 and 10.  Laboratory test included Serial negative inspiratory force (NIF) readings which were obtained, with improvement from -20 to more than -40 and subsequent successful extubation.   The MG crisis was attributed to the second dose of the Moderna COVID-19 vaccine.  This literature non-study case that concerns a 77-year-old, male patient with past medical history of Myasthenia gravis for five years and on prednisone and pyridostigmine, who experienced the unexpected serious AESI events of Myasthenia gravis (aggravated), Myasthenia gravis crisis and Acute kidney injury and unexpected serious event of Respiratory failure which occurred approximately five and one weeks after the first and second doses of mRNA-1273 vaccine. It was reported that patient went to emergency room with complaints of dysphagia for one week. The dysphagia was associated with non-specific arthralgia, intermittent fevers, chills, and fatigue. In the ER, vitals were notable for tachypnea, tachycardia and hypoxia. An electrocardiogram showed sinus tachycardia. Chest x-ray was negative for any infiltrates, effusions, or consolidations. Labs were significant for acute renal failure (due to poor oral intake). The septic workup was negative. He was admitted to the neuro with Myasthenia gravis exacerbation and was started on pyridostigmine, prednisone and IV immunoglobulin. His acute renal failure resolved with adequate IV hydration. He was acutely decompensated, an arterial blood gas analysis (ABG) confirmed acute hypercapnic respiratory failure for which the patient was intubated and transferred to the medical intensive care unit (MICU). He was started on prednisone and another two IVIg were given. Serial negative inspiratory force (NIF) readings were obtained, with improvement from -20 to more than -40 and subsequent successful extubation. Patients past medical history of Myasthenia gravis remains as a confounder. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 25-Feb-2022: Follow up received by safety on 25-Feb-2022 included an Email with report received from RA team and contains significant information. Initial and follow up  processed together.; Sender's Comments: This literature non-study case that concerns a 77-year-old, male patient with past medical history of Myasthenia gravis for five years and on prednisone and pyridostigmine, who experienced the unexpected serious AESI events of Myasthenia gravis (aggravated), Myasthenia gravis crisis and Acute kidney injury and unexpected serious event of Respiratory failure which occurred approximately five and one weeks after the first and second doses of mRNA-1273 vaccine. It was reported that patient went to emergency room with complaints of dysphagia for one week. The dysphagia was associated with non-specific arthralgia, intermittent fevers, chills, and fatigue. In the ER, vitals were notable for tachypnea, tachycardia and hypoxia. An electrocardiogram showed sinus tachycardia. Chest x-ray was negative for any infiltrates, effusions, or consolidations. Labs were significant for acute renal failure (due to poor oral intake). The septic workup was negative. He was admitted to the neuro with Myasthenia gravis exacerbation and was started on pyridostigmine, prednisone and IV immunoglobulin. His acute renal failure resolved with adequate IV hydration. He was acutely decompensated, an arterial blood gas analysis (ABG) confirmed acute hypercapnic respiratory failure for which the patient was intubated and transferred to the medical intensive care unit (MICU). He was started on prednisone and another two IVIg were given. Serial negative inspiratory force (NIF) readings were obtained, with improvement from -20 to more than -40 and subsequent successful extubation. Patients past medical history of Myasthenia gravis remains as a confounder. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.