graves disease/TSH was dropping drastically/it was dropping even lower; This spontaneous case was reported by a patient and describes the occurrence of BASEDOW'S DISEASE (graves disease/TSH was dropping drastically/it was dropping even lower) in a 33-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 030H21B) for COVID-19 prophylaxis.     She has no family history of graves disease.  The patient's past medical history included Gallbladder removal (Gall bladder was removed in July 2022) in July 2022. Previously administered products included for COVID-19 prophylaxis: Moderna COVID-19 Vaccine (First dose, lot 039K20A) on 11-Jan-2021, Moderna COVID-19 Vaccine (Second dose and lot 028L20A) on 08-Feb-2021. Past adverse reactions to the above products included No adverse event with Moderna COVID-19 Vaccine and Moderna COVID-19 Vaccine.    On 06-Dec-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 06-Dec-2022,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced BASEDOW'S DISEASE (graves disease/TSH was dropping drastically/it was dropping even lower) (seriousness criterion medically significant). The patient was treated with METHIMAZOLE on 20-Dec-2022 at a dose of 10 milligram once a day. At the time of the report, BASEDOW'S DISEASE (graves disease/TSH was dropping drastically/it was dropping even lower) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 09-Dec-2022, Blood thyroid stimulating hormone: her TSH was dropping drastically. On 13-Dec-2022, Blood thyroid stimulating hormone: was dropping even lower. On an unknown date, Laboratory test: had labs done in November, and her thyroid levels were normal, TSH receptor test came back positive for Graves disease.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   No concomitant medications were reported.   Patient did not receive any other vaccines in the 4 weeks prior to COVID-19 vaccine.  The patient had labs done in November, and her thyroid levels were normal. She got sick on 06-Dec-2022, exactly one year after getting her booster shot. On 09-Dec-2022, her TSH was dropping drastically. On 13-Dec-2022, it was dropping even lower. On 16-Dec-2022, it was determined that she needed to see a specialist. On 20-Dec-2022, she was diagnosed with Graves disease.   It was reported that this was now a disease that she has to live with for the rest of her life. It was supposed to save her, not make her sick.  The symptom of Graves' disease included 'got sick'.  Company comment: This spontaneous case concerns a 33-year-old female patient, with no relevant medical history reported who experienced the unexpected serious (medically significant) event of Basedow's disease that occurred approximately one year after receiving the third dose of mRNA-1273 vaccine in COVID-19 vaccination series. Patient has received initial two doses of Moderna vaccine at an interval of 28 days. One year after vaccination (third dose) , patient got sick. Her TSH was dropping drastically. Approximately 14 days later, she was diagnosed with Graves' disease. No further information on risk factors, detailed clinical course, medical history, concurrent conditions, additional investigations and treatment received were provided. The outcome of the event was not recovered. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This spontaneous case concerns a 33-year-old female patient, with no relevant medical history reported who experienced the unexpected serious (medically significant) event of Basedow's disease that occurred approximately one year after receiving the third dose of mRNA-1273 vaccine in COVID-19 vaccination series. Patient has received initial two doses of Moderna vaccine at an interval of 28 days. One year after vaccination (third dose) , patient got sick. Her TSH was dropping drastically. Approximately 14 days later, she was diagnosed with Graves' disease. No further information on risk factors, detailed clinical course, medical history, concurrent conditions, additional investigations and treatment received were provided. The outcome of the event was not recovered. The benefit-risk relationship of mRNA-1273 is not affected by this report.