Guillain Barr Syndrome; neurological effects; Diarrhea; His demeanor, personality, his entire self went from light to dark over night; His demeanor, personality, his entire self went from light to dark over night; Feeling of weakness and unwell; Feeling of weakness and unwell; He speaks, walks, and reacts very slow; He speaks, walks, and reacts very slow; He speaks, walks, and reacts very slow; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP).  A 85 year-old male patient received bnt162b2 (BNT162B2), administered in arm right, administration date 22Feb2021 10:00 (Lot number: EN6202) at the age of 85 years as dose 2, single for covid-19 immunisation. Relevant medical history included: "known_allergies:Penicillin" (unspecified if ongoing), notes: known_allergies:Penicillin. There were no concomitant medications. Vaccination history included: Bnt162b2 (Covid vaccine details:, Product=COVID 19, Brand= Pfizer, Lot number= EN5318, Lot unknown=False, Administration date=23Jan2021, Administration time=10:15 AM, Vaccine location=Right arm, Dose number=1), administration date: 23Jan2021, when the patient was 85 years old, for COVID-19 immunisation. The following information was reported: GUILLAIN-BARRE SYNDROME (medically significant), outcome "unknown", described as "Guillain Barr Syndrome"; NEUROLOGICAL SYMPTOM (non-serious), outcome "unknown", described as "neurological effects"; DIARRHOEA (non-serious) with onset 04Apr2021 10:00, outcome "not recovered", described as "Diarrhea"; ABNORMAL BEHAVIOUR (non-serious), PERSONALITY CHANGE (non-serious) all with onset 04Apr2021 10:00, outcome "not recovered" and all described as "His demeanor, personality, his entire self went from light to dark over night"; ASTHENIA (non-serious), MALAISE (non-serious) all with onset 04Apr2021 10:00, outcome "not recovered" and all described as "Feeling of weakness and unwell"; LETHARGY (non-serious), SLOW SPEECH (non-serious), BRADYKINESIA (non-serious) all with onset 04Apr2021 10:00, outcome "not recovered" and all described as "He speaks, walks, and reacts very slow". The events "diarrhea", "his demeanor, personality, his entire self went from light to dark over night", "his demeanor, personality, his entire self went from light to dark over night", "feeling of weakness and unwell", "feeling of weakness and unwell", "he speaks, walks, and reacts very slow", "he speaks, walks, and reacts very slow" and "he speaks, walks, and reacts very slow" were evaluated at the physician office visit. The patient underwent the following laboratory tests and procedures: magnetic resonance imaging: (2021) nothing significant came back as wrong, notes: He labs and even an MRI nothing significant came back as wrong. Therapeutic measures were not taken as a result of diarrhoea, abnormal behaviour, personality change, asthenia, malaise, lethargy, slow speech, bradykinesia.  Additional information: Patient had a bad experience with diarrhea. After that he completely changed. AE resulted in Doctor or other healthcare professional office/clinic. The patient did not received other vaccine in four week and Other medications in two weeks. Prior to vaccination, the patient was not diagnosed with COVID. Post vaccination, the patient has not been tested for COVID-19. Other medical history was none.  No follow-up attempts are possible. No further information is expected.