feeling terrible; dizzy; disoriented; vertigo; Blood Glucose in 500-600; hematocrit dropped from 35-36 to 20; lost weight; This is a spontaneous report received from a contactable reporter(s) (Physician) from medical information team.  A 87 year-old male patient received bnt162b2 (COMIRNATY), administration date Feb2021 (Batch/Lot number: unknown) at the age of 87 years as dose 2, single for covid-19 immunisation. Relevant medical history included: "pancreatic carcinoma" (unspecified if ongoing), notes: is getting radiation and may need chemotherapy. There were no concomitant medications. Vaccination history included: Bnt162b2 (first dose lot unknown), for COVID-19 immunisation. The following information was reported: FEELING ABNORMAL (hospitalization) with onset Apr2021, outcome "unknown", described as "feeling terrible"; DIZZINESS (hospitalization) with onset Apr2021, outcome "unknown", described as "dizzy"; DISORIENTATION (hospitalization) with onset Apr2021, outcome "unknown", described as "disoriented"; VERTIGO (hospitalization) with onset Apr2021, outcome "recovered" (2021), described as "vertigo"; BLOOD GLUCOSE ABNORMAL (hospitalization) with onset Apr2021, outcome "unknown", described as "Blood Glucose in 500-600"; HAEMATOCRIT DECREASED (hospitalization, medically significant, life threatening) with onset Apr2021, outcome "recovered" (2021), described as "hematocrit dropped from 35-36 to 20"; WEIGHT DECREASED (non-serious), outcome "unknown", described as "lost weight". The patient was hospitalized for feeling abnormal, dizziness, disorientation, vertigo, blood glucose abnormal, haematocrit decreased (start date: Apr2021). The patient underwent the following laboratory tests and procedures: blood glucose: 500-600; haematocrit: dropped from 35-36 to 20; back up to 35. Therapeutic measures were taken as a result of feeling abnormal, dizziness, disorientation, vertigo, blood glucose abnormal, haematocrit decreased. The patient received the second dose in Feb2021 and 6 weeks later he was hospitalized for a week in mid Apr2021 (correct date per HCP) for feeling terrible, dizzy, disoriented, vertigo, Blood Glucose in 500-600 hematocrit dropped from 35-36 to 20. He got better in a week or so. HCP unable to find any other cause for these symptoms. Per caller: Patient received fluids, got a few blood units , bone marrow, blood test was normal, he went home on 4-5 units of Lantus a  day. he was not on insulin before. His hematocrit is back up to 35, vertigo and lightheadedness have not retuned. Patient has cystic lesion/pancreatic carcinoma, he was easy to manage before and now his diabetes /Blood Glucose are out of control. he received the radiation without any problem, lost weight. When caller last spoke to the patient he was feeling fine jumping to get the booster dose of the vaccine. Caller wanted to know if there symptoms have been reported. He was hospitalized and no one found out what this was and then the patient got better within a week. The patient while hospitalized had a couple of blood transfusions and checked bone marrow and had an extension work up and everything was fine. He recovered completely but just is on 2 to 3 units of insulin today, his hematocrit is back to 35 and the vertigo has gone away. Someone the caller was talking to had asked how do they know that this was not caused by the vaccine even though it was roughly 6 weeks afterwards? The patient wants to get the booster dose because he is high risk being an 88-year-old diabetic with cancer but the caller doesn't know whether to give the patient the booster or not. He wants to know Pfizer's recommendation on this. The caller is in a dilemma because the family is getting worried about the booster and the patient is adamite to getting it. Maybe there is no answer to this but the caller decided that this was the simplest way to get to the solution. The patient was 199 pounds but lost about 20 pounds so make him about 170 pounds now since he has lost weight. Event Details: Caller states that the patient was hospitalized around early May2021, so it was at least a couple of months after he had the vaccine (documented as provided by caller). Caller says that for the most part the patient recovered within a week, he was debilitated from some but the major abnormal things had disappeared within a week, his blood sugars were easy to control, his anemia was gone once he had the transfusions and the vertigo went away. His bone marrow didn't show anything and the anemia wasn't form blood loss. Seriousness: It was medically significant and life threatening. Patients in their 80's don't do well with low 20's as their hematocrit. While he was in the hospital he didn't arrest or anything like that because he got there before he fell apart. They gave him fluids and insulin and were able to straighten him out. He hasn't known this man long term but he has known him for at least 5 to 6 weeks and the patient blood sugars were very easy to control, he wasn't even on insulin and now he is only on a couple of units. Something happened but it is obvious that the time interval is wide enough that it may not have anything to do with the vaccine. But someone shot as a possibility because every side effect that you can't find a cause for you blame on the vaccine. The patient is just so adamite about wanting the vaccine and that puts the caller in a bad position because if this whole thing happens again then where will they be at? The caller is beginning to think that it is less likely to be from the vaccine given the interval being a couple of months between these things. History/ Investigations: No, but they did found out from working on him during all of this that he had a lesion that was pancreatic cancer. It was found during all of this but his blood sugars came down before the cancer was treated and that is probably related. Causality: He doesn't know and that's the trouble. Given the time interval of a couple of months he is going to say that it is probably unlikely. Relatedness of drug to reaction(s)/event(s)  Reaction assessed: felt terrible, dizzy, Disorientated, Vertigo, Blood Glucose in 500-600, hematocrit dropped from 35-36 to 20 Source of assessment: Primary Source Reporter  Method of assessment: Global Introspection Drug result: Unrelated      The reporter considered "feeling terrible", "dizzy", "disoriented", "vertigo", "blood glucose in 500-600" and "hematocrit dropped from 35-36 to 20" not related to bnt162b2.  The lot number for bnt162b2 was not provided and will be requested during follow up.; Sender's Comments: The events of feeling abnormal, dizziness, disorientation, vertigo, blood glucose abnormal, haematocrit decreased is assessed as possibly related to the suspect drug "BNT162B2" based on strong temporal association, but consider also possible contributory effects from patient's medical history and/or concomitant medical ongoing medical therapy - chemotherapy.  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.