pain; shaking violently the whole day; very bad GI thing; my heart was doing some crazy things like fibrillating; sick; fever; arm pain under the armpit; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP) from medical information team. The reporter is the patient.  A 71-year-old female patient received BNT162b2, BNT162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), as dose 3 (booster), single (Batch/Lot number: unknown) at the age of 71 years for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Bnt162b2 (Dose Number: 2, Lot: Not provided, Manufacture: Pfizer), for COVID-19 immunization; Bnt162b2 (Dose Number: 1, Lot: Not provided, Manufacture: Pfizer), for COVID-19 immunization. The following information was reported: ATRIAL FIBRILLATION (medically significant), outcome "unknown", described as "my heart was doing some crazy things like fibrillating"; ILLNESS (non-serious), outcome "unknown", described as "sick"; PYREXIA (non-serious), outcome "recovered", described as "fever"; PAIN (non-serious), outcome "unknown"; TREMOR (non-serious), outcome "unknown", described as "shaking violently the whole day"; GASTROINTESTINAL DISORDER (non-serious), outcome "unknown", described as "very bad GI thing"; AXILLARY PAIN (non-serious), outcome "recovered", described as "arm pain under the armpit". The event "very bad gi thing" required physician office visit.  Patient had first two doses of the Pfizer COVID-19 vaccine, and then one booster. She did not get anything after that. She was very sick. Being so sick, she didn't want to get any more vaccines.  had fever for 2 days and arm pain for 7 days, under the armpit. Patient also was shaking violently the whole day. She had a very bad GI thing happening to her. My doctor prescribed antibiotics and she was left with no good bacteria. she had to take probiotics and change her diet. Also, her heart was doing some crazy things like fibrillating. After some time, it went back to sinus mode. Patient is thinking of getting another, the bivalent booster. But she was reading all over the internet that the XBB variant is immunoevasive. She was considering it, but she heard it doesn't even work against the new variants. She would like to know if the bivalent booster offers any protection against the XBB variants. She would like to know if Pfizer is working on developing another version of the COVID-19 vaccine to protect against these new subvariants. There doesn't seem to be any new development specific for that strain of the virus. Clarifies upon transfer that the gastrointestinal issue was not from the vaccine. The reason she did not get the 4th and 5th booster was because she had gotten sick. She read online that everything she experienced is normal and did not get anything abnormal. Therapeutic measures were taken as a result of gastrointestinal disorder.  The reporter considered "very bad gi thing" not related to BNT162b2, BNT162b2 omi ba.4-5. The events were considered non-serious by the reporting consumer.  The information on the batch/lot number for BNT162b2, BNT162b2 omi ba.4-5 has been requested and will be submitted if and when received.