Diarrhea; Severe cramps; Vomiting; Nausea; she is really terrible right now; She got really sick and she is been sick ever since; Stomach Flu; Booster; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP).  A 70 year-old female patient received bnt162b2 (BNT162B2), intramuscular, administered in arm right, administration date 27Oct2021 15:00 (Lot number: EW0217) at the age of 70 years as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "Stomach Flu", start date: 31Oct2021, stop date: 07Nov2021. There were no concomitant medications. Vaccination history included: Bnt162b2 (first dose, Time(24hr): Afternoon, Anatomical site of injection: Arm, Route of administration: Intramuscular, Lot No: ER2613), administration date: 18Mar2021, when the patient was 70 years old, for COVID-19 Immunization; Bnt162b2 (second dose, Time(24hr): Afternoon, Anatomical site of injection: Arm, Route of administration: Intramuscular, Lot No: EW0158), administration date: 08Apr2021, when the patient was 70 years old, for COVID-19 Immunization. The following information was reported: IMMUNISATION (non-serious) with onset 27Oct2021 15:00, outcome "unknown", described as "Booster"; DIARRHOEA (non-serious) with onset 31Oct2021, outcome "unknown", described as "Diarrhea"; MUSCLE SPASMS (non-serious) with onset 31Oct2021, outcome "unknown", described as "Severe cramps"; VOMITING (non-serious) with onset 31Oct2021, outcome "unknown", described as "Vomiting"; NAUSEA (non-serious) with onset 31Oct2021, outcome "unknown", described as "Nausea"; MALAISE (non-serious) with onset 31Oct2021, outcome "unknown", described as "she is really terrible right now"; ILLNESS (non-serious) with onset 31Oct2021, outcome "unknown", described as "She got really sick and she is been sick ever since"; GASTROENTERITIS VIRAL (non-serious) with onset 31Oct2021, outcome "recovered" (07Nov2021), described as "Stomach Flu". Therapeutic measures were not taken as a result of diarrhoea, muscle spasms, vomiting, nausea, malaise, illness.  Additional information: Reporter is patient's husband. Reporter stated, my wife withheld received a booster vaccination (unspecified vaccine) 4 days ago. Today she has severe cramps, diarrhea, vomiting and nausea. Reporter was informed about the role of Pfizer Drug Safety and requested to probe. LOT: Reporter stated, Looks like EW0217. First one was ER2613. Still experiencing the problem: Reporter stated, yes, she is really terrible right now. I wonder what to do with her. Outcome of event: Reporter stated, well she was fine up until 3 o'clock today and then she got really sick and she is been sick ever since. Treatment taken: Reporter stated, no. Date of adverse event: Reporter stated, today like about 4 hours ago, 5 hours ago so the 31Oct2021). Anatomical site of vaccine administration: Reporter stated, it was on the right arm. Anything else to help with: Reporter stated, I wonder if you have any suggestions as to what she should do about all these problems which she is been experiencing right now. Patient did not receive any other vaccines prior vaccination. Comments/Narrative: We no longer believe that her illness was a result of the COVID vaccination. A visit to urgent care resulted in diagnosis of the stomach flu instead we are sorry to have bothered you folks.  No follow-up attempts are possible. No further information is expected.