New onset bulbar myasthenia gravis; Third full dose received in August 2021 outside the recommended guidelines; Patient received third full dose 4 months after second dose; This literature-non-study case was reported in a literature article and describes the occurrence of MYASTHENIA GRAVIS (New onset bulbar myasthenia gravis) in a 60-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.   LITERATURE REFERENCE:     No Medical History information was reported.   In March 2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. In August 2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. In 2021,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced MYASTHENIA GRAVIS (New onset bulbar myasthenia gravis) (seriousness criteria hospitalization and medically significant). On an unknown date, the patient experienced OFF LABEL USE (Third full dose received in August 2021 outside the recommended guidelines) and INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (Patient received third full dose 4 months after second dose). At the time of the report, MYASTHENIA GRAVIS (New onset bulbar myasthenia gravis), OFF LABEL USE (Third full dose received in August 2021 outside the recommended guidelines) and INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (Patient received third full dose 4 months after second dose) outcome was unknown. Related.    DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In 2021, Electromyogram: confirmed of new onset bulbar myasthenia gravis. In 2021, Nerve stimulation test: confirmed of new onset bulbar myasthenia gravis.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered MYASTHENIA GRAVIS (New onset bulbar myasthenia gravis), OFF LABEL USE (Third full dose received in August 2021 outside the recommended guidelines) and INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (Patient received third full dose 4 months after second dose) to be related.    Patient received a 2nd dose mRNA-1273 vaccine in March 2021 and a 3rd dose of mRNA-1273 vaccine in August 2021. Symptoms began as dysphagia, dysarthria, diplopia, and weakness. Progression of symptoms led to dehydration and malnutrition prompting hospitalization. Lab tests and evaluation confirmed the diagnosis of new onset bulbar myasthenia. Booster dose vaccination was approved in October 2021. Further details on the medical history, clinical course including the intention behind administration of his 3rd vaccination prior to the approved guidelines (Product use issue), concomitant medications, and treatments were not reported in the abstract. CC: This literature case concerns a 60-year-old, male patient with no reported medical history, who experienced an unexpected, medically significant AESI Myasthenia gravis 6 days after receiving a 3rd dose of mRNA-1273 vaccine that led to hospitalization. Patient initially presented with dysphagia, dysarthria, diplopia, and weakness. Over the next month, symptoms progressed resulting to dehydration and malnutrition prompting hospitalization. Evaluation, lab data, repetitive nerve stimulation studies, and needle electromyography confirmed the diagnosis of new onset bulbar myasthenia on an unknown date. Vaccination history included a 2nd dose of mRNA-1273 vaccine, given 4 months before his 3rd vaccination. Booster dose guideline was approved only after 2 months from his 3rd vaccination. The benefit-risk relationship of mRNA-1273 is not affected by this report. Event's seriousness assessed based on medical judgement and the available information. Sender's Comments: This literature case concerns a 60-year-old, male patient with no reported medical history, who experienced an unexpected, medically significant AESI Myasthenia gravis 6 days after receiving a 3rd dose of mRNA-1273 vaccine that led to hospitalization. Patient initially presented with dysphagia, dysarthria, diplopia, and weakness. Over the next month, symptoms progressed resulting to dehydration and malnutrition prompting hospitalization. Evaluation, lab data, repetitive nerve stimulation studies, and needle electromyography confirmed the diagnosis of new onset bulbar myasthenia on an unknown date. Vaccination history included a 2nd dose of mRNA-1273 vaccine, given 4 months before his 3rd vaccination. Booster dose guideline was approved only after 2 months from his 3rd vaccination. The benefit-risk relationship of mRNA-1273 is not affected by this report. Event's seriousness assessed based on medical judgement and the available information.