Graves' Disease; This literature-non-study case was reported in a literature article and describes the occurrence of BASEDOW'S DISEASE (Graves' Disease) in a 42-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.       No Medical History information was reported.   On 03-Nov-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced BASEDOW'S DISEASE (Graves' Disease) (seriousness criterion medically significant). The patient was treated with METHIMAZOLE at an unspecified dose and frequency and PROPRANOLOL at an unspecified dose and frequency. At the time of the report, BASEDOW'S DISEASE (Graves' Disease) outcome was unknown. Related    DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Anti-thyroid antibody (less than 5.6-Unknown): 70.25 iu/ml (High) microsomal antibodies were elevated at 70.25 IU/ml). On an unknown date, Blood thyroid stimulating hormone (0.45-4.5): less than  0.015 mciu/ml (Low) TSH less than 0.015 mcIU/ml. On an unknown date, C-reactive protein: less than 0.9 C-reactive protein was less than 0.9. On an unknown date, Heart rate: 110/min heart rate of 110/min at rest. On an unknown date, Influenza virus test: negative (Negative) Influenza virus B was negative and negative (Negative) Influenza virus A was  negative. On an unknown date, Physical examination: tachycardia Physical examination revealed tachycardia. On an unknown date, SARS-CoV-2 test: negative (Negative) Covid-19 polymerase chain reaction (PCR) was negative. On an unknown date, Scan thyroid gland: bilateral avid symmetric radionuclide uptake Thyroid scan showed bilateral avid symmetric radionuclide uptake consistent with a hyperfunctioning gland. Thyroid uptake and scan with technetium 99 pertechnetate showing avid uptake. On an unknown date, Thyroid function test: normal (normal) normal thyroid function but developed hyperthyroidism characterized by suppressed thyroid-stimulating hormone. On an unknown date, Thyroid stimulating immunoglobulin (<1.75-Unknown): 16.1 iu/l (High) TSH receptor antibody was markedly elevated at 16.1 IU/L. On an unknown date, Thyroxine free (0.78-2.19): 5.96 ng/dl (High) free T4 5.96 ng/dl. On an unknown date, Ultrasound thyroid: prominent heterogeneous Thyroid ultrasound showed a prominent heterogeneous and hyperemic gland, increased vascularity in the entire right lobe. On an unknown date, White blood cell count (4-10.5): 4.1k/microliter (normal) WBC count was 4.1 k/microliter.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered BASEDOW'S DISEASE (Graves' Disease) to be related.    No concomitant medications were provided.  Patient had no previous of thyroid disease.  Patient developed nausea, significant muscle weakness, shortness of breath on exertion, excessive sweating, headache, and difficulty sleeping at night two days later. He lost 20 pounds within 11 days of his vaccination.  Company Comment: This is a literature case that concerns a 42-year-old male patient with no medical history reported, who experienced the unexpected serious (medically significant) event of Basedow's disease (Graves' disease) unspecified days after the third dose of mRNA-1273 vaccine. Two days after the vaccine patient developed nausea, significant muscle weakness, shortness of breath on exertion, excessive sweating, headache, and difficulty sleeping at night. He lost 20 pounds within 11 days of his vaccination. On an unknown date, physical examination revealed tachycardia with a heart rate of 110/min at rest, Laboratory tests showed that WBC count was 4.1 k/microliter (4-10.5), Influenzavirus A and B were negative, Covid-19 polymerase chain reaction (PCR) was negative, C-reactive protein was less than 0.9. Thyroid studies showed TSH less than 0.015 mcIU/ml and free T4 5.96. TSH receptor antibody was markedly elevated at 16.1 IU/L and microsomal antibodies were elevated at 70.25, Thyroid ultrasound showed a prominent heterogeneous and hyperemic gland and Thyroid technetium 99 scan showed bilateral avid symmetric radionuclide uptake consistent with a hyperfunctioning gland. The patient was started on with methimazole and propranolol. Conclusion for the study will be that the clinicians must be vigilant for diagnosis of hyperthyroidism, including Graves' disease in patients after recent covid-19 vaccination. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.; Sender's Comments: This is a literature case that concerns a 42-year-old male patient with no medical history reported, who experienced the unexpected serious (medically significant) event of Basedow's disease (Graves' disease) unspecified days after the third dose of mRNA-1273 vaccine. Two days after the vaccine patient developed nausea, significant muscle weakness, shortness of breath on exertion, excessive sweating, headache, and difficulty sleeping at night. He lost 20 pounds within 11 days of his vaccination. On an unknown date, physical examination revealed tachycardia with a heart rate of 110/min at rest, Laboratory tests showed that WBC count was 4.1 k/microliter (4-10.5), Influenzavirus A and B were negative, Covid-19 polymerase chain reaction (PCR) was negative, C-reactive protein was less than 0.9. Thyroid studies showed TSH less than 0.015 mcIU/ml and free T4 5.96. TSH receptor antibody was markedly elevated at 16.1 IU/L and microsomal antibodies were elevated at 70.25, Thyroid ultrasound showed a prominent heterogeneous and hyperemic gland and Thyroid technetium 99 scan showed bilateral avid symmetric radionuclide uptake consistent with a hyperfunctioning gland. The patient was started on with methimazole and propranolol. Conclusion for the study will be that the clinicians must be vigilant for diagnosis of hyperthyroidism, including Graves' disease in patients after recent covid-19 vaccination. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.