Onset of delirium; altered mental status; confusion; vomiting; headache; Completely disoriented; has no memory of events.; Booster; This is a spontaneous report received from a contactable reporter(s) (Physician).  A 69 year-old female patient (not pregnant) received bnt162b2 (BNT162B2), intramuscular, administered in arm left, administration date 09Dec2021 14:15 (Lot number: FD0809) at the age of 69 years as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "Diabetes" (unspecified if ongoing); "obesity" (unspecified if ongoing); "chronic pain" (unspecified if ongoing); "hypertension" (unspecified if ongoing); "hyperlipidemia" (unspecified if ongoing); "Hashimoto's thyroiditis" (unspecified if ongoing); "GERD" (unspecified if ongoing). Patient didn't have Covid prior vaccination. Concomitant medication(s) included: FUROSEMIDE; GABAPENTIN; GLIPIZIDE; AZITHROMYCIN; IRBESARTAN; PRALUENT; ESOMEPRAZOLE MAGNESIUM. No other vaccine in four weeks. Vaccination history included: Bnt162b2 (Dose 2, lot number: EW0153, administrator route: Intramuscular, administration time: 02:15 PM, location: Left arm.), administration date: 09Apr2021, when the patient was 68 years old, for COVID-19 immunization; Bnt162b2 (Dose 1, lot number: ER2613, administrator route: Intramuscular, administration time: 02:15 PM, location: Left arm), administration date: 19Mar2021, when the patient was 68 years old, for COVID-19 immunization. The following information was reported: IMMUNISATION (hospitalization) with onset 09Dec2021 14:15, outcome "unknown", described as "Booster"; DELIRIUM (hospitalization) with onset 10Dec2021 01:00, outcome "recovering", described as "Onset of delirium"; MENTAL STATUS CHANGES (hospitalization) with onset 10Dec2021 01:00, outcome "recovering", described as "altered mental status"; CONFUSIONAL STATE (hospitalization) with onset 10Dec2021 01:00, outcome "recovering", described as "confusion"; VOMITING (hospitalization) with onset 10Dec2021 01:00, outcome "recovering", described as "vomiting"; HEADACHE (hospitalization) with onset 10Dec2021 01:00, outcome "recovering", described as "headache"; DISORIENTATION (hospitalization) with onset 10Dec2021 01:00, outcome "recovering", described as "Completely disoriented"; MEMORY IMPAIRMENT (hospitalization) with onset 10Dec2021 01:00, outcome "recovering", described as "has no memory of events.". Clinical course: Onset of delirium, altered mental status, confusion, vomiting, headache within about 10-12 hours of vaccine. Completely disoriented for 24 hours and has no memory of events. The patient was hospitalized for immunisation, delirium, mental status changes, confusional state, vomiting, headache, disorientation, memory impairment (hospitalization duration: 1 day(s)). The events "onset of delirium", "altered mental status", "confusion", "vomiting", "headache", "completely disoriented" and "has no memory of events" were evaluated at the physician office visit and emergency room visit. Therapeutic measures were taken as a result of delirium, mental status changes, confusional state, vomiting, headache, disorientation, memory impairment, which included: IV fluids, observation, imaging, labs. The patient underwent the following laboratory tests and procedures: sars-cov-2 test: (10Dec2021) negative, notes: Nasal Swab.; Sender's Comments: Based on known drug safety profile, there is reasonable possibility of causal association between the events and BNT162B2.  The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.