hyperthyroidism/hyperthyroid symptoms; Graves' disease; then sub sequentially developed severe graves eye disease; toxic goiter; This is a spontaneous report from a contactable physician. A 69-year-old male patient received second dose of BNT162B2 in Jan2021 (at age of 69-year-old) at single dose for COVID-19 immunization. Medical history included diabetes and doesn't smoke. Concomitant medications were none. Historical vaccine included first dose of BNT162B2 in Jan2021 (at age of 69-year-old) for Covid-19 Immunization. Patient completed his two dose vaccination series in Jan2021. Patient developed hyperthyroidism 2-3 weeks post vaccination (Feb2021) which later progressed to Graves disease. He has been treated with radioactive iodine in Mar2021. He developed graves eye disease which was treated with IV infusion Tapasa and Steroids. Caller reported the therapy seemed to work pretty well. Patient has a medical history of diabetes. Caller wants to know if the patient is eligible to receive the booster of the Pfizer COVID-19 vaccine. Caller is also interested to know if the IgG level will flare up if he gets the third dose of the vaccine. Caller says that he is an endocrinologist and he has been seeing a patient for graves disease. The patient had informed him that he had the Pfizer vaccine in Jan2021 and within 2 to 3 weeks he developed hyperthyroid symptoms and then was diagnosed with graves disease. The caller did a literature search and there are some reports of hyperthyroidism being reported after the COVID vaccination. The patient then sub sequentially developed severe graves eye disease and had a Tepezza infusion for the graves eye disease. It has improved and the patient has been doing better and the graves disease has since been treated. The question came up on whether the patient needs the booster or not. The patient does meet the criteria for it since he is diabetic and over age 65 and so on but the question that the caller has also is if the graves disease was triggered by the COVID vaccine then is it wise to give the patient the booster. To add another complication the caller did check the patient's IGG antibodies for COVID and the report came back negative, which is unexcepted. The caller is calling to see if Pfizer has any thoughts on this case and maybe able to provide some guidance as to what Pfizer recommend him to do for the patient. The story is basically that the patient had the Pfizer COVID vaccine in Jan2021 and then had graves disease within 2 to 3 weeks of getting the 2nd dose. He had developed graves disease and the sub sequentially developed graves eye disease, it is harder to treat both of those conditions. Caller states that these developed within Feb2021 and he confirms that it has been treated since then. The patient initially received radioactive iodine in Mar2021 for his toxic goiter and then for the graves eye disease he was put on steroids and then has also received Tepezza infusions and has responded well to that. History/ Investigations: The only kind of medically relevant event was the COVID vaccine. The patient doesn't smoke and he doesn't have other classic risk factors for graves disease, he is a male. So anyway he would say that the COVID vaccine was the only thing that is medically relevant prior to developing graves disease. The outcome of the events was recovered. The seriousness was reported as medically significant. Relatedness of drug to reaction(s)/event(s): Reaction assessed: developed hyperthyroid symptoms, Graves disease, then sub sequentially developed severe graves eye disease, Source of assessment: Primary Source Reporter, Method of assessment: Global Introspection, Drug result: Related. Reaction assessed: Graves disease. Causality: In his opinion he thinks that there is strong suspicion that there may be a relationship because the patient really didn't have any other medical reason for this to happen, it just kind of happened to come within 2 to 3 weeks of having the COVID vaccine. He just is reporting to say hey maybe there is something there and he wanted to make Pfizer aware of that timeline.  The lot number for the vaccine, [BNT162B2], was not provided and will be requested during follow up.; Sender's Comments: Based on the known safety profile of the vaccine BNT162B2, a temporal relation between the events (Hyperthyroidism, Basedow's disease, Endocrine ophthalmopathy,Toxic goitre )and the administration of the vaccine cannot be excluded.The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events.  Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.