This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient. A 60 year-old female patient received bnt162b2 (BNT162B2, solution for injection), administered in arm left, administration date 04Nov2021 (Lot number: FH8028) at the age of 60 years as dose 3 (booster), single for Covid-19 immunisation. Relevant medical history included: "high cholesterol", start date: Dec2008 (unspecified if ongoing), notes: on cholesterol meds for years. she takes Simvastatin 40mg once daily for high cholesterol.; "Barrett's esophagus", start date: Jun2019 (unspecified if ongoing). Concomitant medication(s) included: NEXIUM 24HR; SIMVASTATIN taken for blood cholesterol increased; FLUARIX QUADRIVALENT taken for immunisation, administration date 12Oct2021. Vaccination history included: Bnt162b2 (1st dose, Pfizer BioNTech Covid-19 vaccine, 0.3ml injected in left arm, lot number: EN6199), administration date: 11Mar2021, when the patient was 59 years old, for Covid-19 immunization, reaction(s): "heart pounding and fluttering", "her heart beating fast and hard", "her heart beating fast and hard", "It has affected her Thyroid"; Bnt162b2 (2nd dose; Pfizer BioNTech Covid-19 vaccine, Lot ER8732; Injected in left arm), administration date: 01Apr2021, when the patient was 59 years old, for Covid-19 immunization, reaction(s): "heart pounding and fluttering", "her heart beating fast and hard", "her heart beating fast and hard", "It has affected her Thyroid"; Fluarix quad 2021/2022 (injection was 0.5ml; Intramuscularly; NDC 58160-0887-52), administration date: 12Oct2021. The following information was reported: HYPERTHYROIDISM (medically significant) with onset 14Feb2022, outcome "unknown", described as "something has created her thyroid to be off which it never had been /her thyroid is overactive all of a sudden/thyroid problems and she's never had thyroid problems"; HEART RATE INCREASED (non-serious), outcome "unknown", described as "her heart beating fast and hard"; PALPITATIONS (non-serious), outcome "unknown", described as "Heart was beating fast and hard and pounding out of"; FEELING HOT (non-serious), ERYTHEMA (non-serious) all with onset 05Nov2021, outcome "recovering" and all described as "Warmth and redness in cheeks"; ALOPECIA (non-serious), outcome "recovering", described as "losing hair"; PAIN IN EXTREMITY (non-serious) with onset 04Nov2021, outcome "recovering", described as "arm sore". According to the caller, when she first went to her doctor on 14Jan due to her concerns about her heart beating harder since the booster vaccine, her doctor stated something has created her thyroid to be off which it never had been but the doctor does not know if it is because of the vaccine. Caller stated her doctor will do a heart monitor on her on 02Mar and her doctor will re-check her thyroid again on 10Mar. Caller stated patient got her labs done for her yearly physical and that's when it showed up about her thyroid. Patient was a pretty healthy person. Patient lost some weight, except for high cholesterol. Caller stated patient was not gonna get the booster but after she did it went all downhill since. She now has thyroid problems and she's never had thyroid problems. Patient was concerned since they are talking about a 4th vaccine and states she will not be getting anymore vaccines as she does not feel comfortable. They called in some medication, and she has not taken it. It was Atenolol 25mg. She was afraid of taking it because it lowers your blood pressure, and she didn't have high blood pressure. She took her blood pressure when her heart was beating fast, and it was 95/61, and she thought about going to the emergency room and did not. Patient got sore immediately after she got it, and got worse, but then better after 3 days. The patient underwent the following laboratory tests and procedures: blood cholesterol: (unspecified date) levels were really good; blood pressure measurement: (unspecified date) down which was at 90/61 or 95/61, notes: it had never been under 100; heart rate: (unspecified date) fast and hard; laboratory test: (unspecified date) showed up about her thyroid; thyroid function test: (11Feb2022) thyroid is out of control. Therapeutic measures were taken with atenolol as a result of heart rate increased, palpitations. Additional information: The heart beating problem is a worry and now she thinks it has affected her thyroid. She is having to go to doctor and having to do a lot of tests. Caller stated she did a lot of reading where it states the antibodies from the vaccine can attack the thyroid causing inflammation and dysfunction of the thyroid after some patients who have had the infection. The caller had her heart beating fast and hard after all of the doses but after the 1st and 2nd dose it had dissipated but after the 3rd it has not dissipated.