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 74-year-old female patient received BNT162b2 (BNT162B2), on 18Mar2021 as dose 2, single (Lot number: EN6206 or EN6266) at the age of 74 years, in left arm for covid-19 immunization. The patient's relevant medical history included: "Asthma" (unspecified if ongoing), notes: She has had asthma for probably 10 years.; "GERD" (unspecified if ongoing); "Acid reflux" (unspecified if ongoing), notes: acid was pushing up in her esophagus; "She was having some stomach discomfort" (unspecified if ongoing); "she has the pushing and pressing on her chest" (unspecified if ongoing). Concomitant medication(s) included: PANTOPRAZOLE taken for gastroesophageal reflux disease; TUMS [CALCIUM CARBONATE] taken for gastroesophageal reflux disease; ROLAIDS [CALCIUM CARBONATE;MAGNESIUM HYDROXIDE] taken for gastroesophageal reflux disease; NEXIUM [ESOMEPRAZOLE SODIUM] taken for gastroesophageal reflux disease. Vaccination history included: BNT162b2 (First dose, Lot Number: EN6198, Route, Anatomical Location: Left upper arm, GERD and acid reflux has disappeared after her COVID-19 vaccines), administration date: 25Feb2021, when the patient was 74-year-old, for COVID-19 Immunization, reaction(s): "GERD and acid reflux has disappeared after her COVID-19 vaccines", "has GERD and acid reflux and this disappeared 2 days after the first shot up to a couple days before her second shot". The following information was reported: THERAPEUTIC RESPONSE UNEXPECTED (non-serious) with onset 18Mar2021, outcome "recovered" (20Mar2021), described as "GERD and acid reflux has disappeared after her COVID-19 vaccines"; DISEASE RECURRENCE (non-serious) with onset 2021, outcome "not recovered", described as "GERD and acid reflux came back before her booster shot".  Additional information: Caller reported a positive reaction to the Pfizer COVID-19 Vaccine. She mentioned that her gastric reflux was gone away. Caller would like to know if there is any information on what is in the vaccine that can cause this acid production to go down. Caller stated that she has had severe acid reflux. However, after getting the Pfizer-BioNTech COVID-19 Vaccine it goes away for a time. Every time she got the vaccine or the booster it disappeared 2-4 days after.  She had it four times and four times her acid reflux has improved. It definitely had something. Indication as Reported by the Primary Source: to protect herself and family from COVID. She was unsuccessfully taking Pantoprazole at the time of her first COVID-19 Vaccine. This worked best of the medications she tried. Worked in the beginning and then stopped working. She had GERD and acid reflux and this disappeared 2 days after the first shot up to a couple days before her second shot and then 2 days after her second shot this went away. She reported the same thing happened after her booster shot as well where the GERD and acid reflux came back before her booster shot and then went away again after. She thought there was something in the product that resolved acid reflux problems. She was not sure if she was cured but her symptoms are gone. She stated 2 days after her first 2 shots of the COVID-19 Vaccine her acid reflux was completely gone. She could have eaten battery acid and this wouldn't have hurt her. 4 days after her first booster COVID-19 vaccine, the acid reflux and GERD was gone and then 5 days after her 2nd booster dose of the COVID-19 Vaccine that she received last week she had no acid reflux and was gone. She hesitated to even get the COVID-19 Vaccine and was afraid the vaccine wouldn't work with her stomach problems. She had her last COVID-19 Vaccine booster dose a week ago Tuesday and feels fine. She doesn't know how long this will last but stated she has such a marked improvement and could breath. She was having some stomach discomfort and as the acid was pushing up in her esophagus. She stated some people had burping but she had the pushing and pressing on her chest. She also had asthma which enhanced her discomfort but all of this was completely gone. The patient received 3rd dose COVID-19 Vaccine Pfizer: Date Received: 09Nov2021, Lot Number: FF8841 and 4th dose COVID-19 Vaccine Pfizer: Date Received: 01Jun2022, Lot Number: FM7553. Caller had no NDC, Lot number, or expiration date for the Tums, Rolaids, Pantoprazole, and Nexium that didn't work. She discarded the medications since the medications weren't working for her acid reflux. She was given a slip of paper from the pharmacy about her vaccine but she left the paper in her car. The patient was 76 years old at time of 4th booster dose of COVID-19 Vaccine. Time the Vaccination Was Given: 01Jun2022 before noon between 11am and 12pm. Anatomical Location of Administration of Pfizer vaccine considered as suspect: left upper arm. Additional vaccines were not administered on same date of the Pfizer suspect. No Prior Vaccinations (within 4 weeks). AE(s) following prior vaccinations: No; she has never had any. No follow-up attempts are possible. No further information is expected.