Booster; He held on on going back to the hospital until he couldn't walk to his front door. Finally, he said he was going back to the hospital again. He went back a week later; fluid on his lungs; Pericarditis; fluid build up between the heart sacs; Pericarditis; fluid build up between the heart sacs; has damage in his heart; chest pain, trouble breathing; chest pain, trouble breathing; high blood pressure; indigestion; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP). The reporter is the patient.  A 63 year-old male patient received bnt162b2 (COVID-19 MANUFACTURER UNKNOWN),  administered in arm right, administration date 22Oct2021 probably 11:00AM-12:00PM (Lot number: 30130BA) at the age of 63 years as dose 3 (booster), single for covid-19 immunisation. The patient had no relevant medical history. There were no concomitant medications. Vaccination history included: Bnt162b2 (Vaccine Name: First number, Lot Number / Expiry Date: Unknown, Route, Anatomical Location:  Left arm), administration date: 21Mar2021, when the patient was 62 years old, for Covid-19 Immunization; Bnt162b2 (Vaccine Name: Second dose, Lot Number / Expiry Date: Unknown, Route, Anatomical Location:  Left arm), administration date: 13Apr2021, when the patient was 62 years old, for Covid-19 Immunization. Right after he got the booster shot, he developed a condition where he had fluid around his heart sac. He clarifies further its like fluid build up between the heart sacs. He didn't realize it was a side effect of the booster, but he was hospitalized for that. He spent 2 days in the hospital and went home and he was still have chest pains and difficulty breathing. He went back to the hospital where he was told he had fluid on his lungs. Initially stated he developed cardiac kinesis. Unable to clarify the spelling of this condition. He later clarifies with his wife the condition is called pericarditis. States its strange. Didn't even know it was a side effect. The doctors couldn't tell him in the hospital how he got it and then the caller spoke with another doctor who informed him that it was a possible side effect of the vaccine. He states he is being sent to too many doctors. He is basically seeing heart doctors. He developed the pericarditis a month after receiving the booster shot. He got the booster shot in October. He initially states he believes he developed pericarditis on 11Nov2021 and at least on 17Nov2021 the antibiotics wore off or they ran out of them. He was still having trouble breathing and fluid developed in his lungs. He states he thought it would go away. He held on going back to the hospital until he couldn't walk to his front door. Finally, he said he was going back to the hospital again. He went back a week later. When probed for the outcome of the pericarditis, the caller state he was told he has damage in his heart and has to go to a heart specialist for that. He states he doesn't know what the heck they are talking about. They ran all sorts of tests including stress test, CAT scan, X-Ray, ultrasound in which now he has to see the heart specialist for. He wasn't on anything. Now, he has to take a high blood pressure medication. The caller states this thing hit him like a rock, he didn't know what it was. He initially thought it was indigestion that wouldn't go away. He thought they maybe he just needed to burp and take antacids. This didn't work and he told his wife what was going on. He explains he couldn't even lay down. He had to sleep sitting up. Finally, he said he had to go to the hospital. The following information was reported: IMMUNISATION (hospitalization, medically significant) with onset 22Oct2021, outcome "unknown", described as "Booster"; PERICARDITIS (hospitalization), PERICARDIAL EFFUSION (hospitalization) all with onset 15Nov2021, outcome "unknown" and all described as "Pericarditis; fluid build up between the heart sacs"; PULMONARY OEDEMA (hospitalization), outcome "unknown", described as "fluid on his lungs"; GAIT DISTURBANCE (hospitalization), outcome "unknown", described as "He held on on going back to the hospital until he couldn't walk to his front door. Finally, he said he was going back to the hospital again. He went back a week later"; MYOCARDIAL INJURY (medically significant), outcome "unknown", described as "has damage in his heart"; CHEST PAIN (non-serious), DYSPNOEA (non-serious), outcome "unknown" and all described as "chest pain, trouble breathing"; HYPERTENSION (non-serious), outcome "unknown", described as "high blood pressure "; DYSPEPSIA (non-serious), outcome "unknown", described as "indigestion". The patient was hospitalized for pericarditis, pericardial effusion, pulmonary oedema (hospitalization duration: 2 day(s)); for gait disturbance (hospitalization duration: 7 day(s)). The events "pericarditis; fluid build up between the heart sacs", "pericarditis; fluid build up between the heart sacs", "fluid on his lungs", "he held on on going back to the hospital until he couldn't walk to his front door. finally, he said he was going back to the hospital again. he went back a week later", "has damage in his heart", "chest pain, trouble breathing" and "chest pain, trouble breathing" were evaluated at the physician office visit and emergency room visit. The patient underwent the following laboratory tests and procedures: cardiac stress test: unknown result, notes: problem with his heart; computerised tomogram: unknown result; ultrasound scan: unknown result; x-ray: unknown result. Therapeutic measures were taken as a result of pericarditis, pericardial effusion, hypertension, dyspepsia.  No follow-up attempts are possible. No further information is expected.