I could not walk; low blood count; 'fully blown' illnesses; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP). The reporter is the patient.  A 74 year-old female patient received bnt162b2 (BNT162B2) (Batch/Lot number: unknown) as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "breast cancer" (unspecified if ongoing), notes: Other Medical Conditions: Consumer stated, "No. I had a breast cancer supposedly from taking Ranitidine, which I do not know if it is true or not. Concomitant medication(s) included: XARELTO; LETROZOLE. Vaccination history included: Bnt162b2 (DOSE 1, SINGLE, Primary series of both the vaccine done, Manufacturer unknown., Consumer stated, "I had a very bizarre reaction to my COVID booster shot (Pfizer COVID Vaccine), the first two shots did not bother me), for COVID-19 immunization; Bnt162b2 (DOSE 2, SINGLE), for COVID-19 Immunization. The following information was reported: GAIT INABILITY (hospitalization), outcome "unknown", described as "I could not walk"; FULL BLOOD COUNT ABNORMAL (hospitalization), outcome "unknown", described as "low blood count"; ILLNESS (hospitalization), outcome "unknown", described as "'fully blown' illnesses". The patient underwent the following laboratory tests and procedures: full blood count: low; investigation: okay, notes: Consumer stated, "Yes, I think so. I mean a couple of weeks ago I was hospitalized and they did the blood work when I left and it was okay then."; parasite blood test: unknown result, notes: So, he tested me for everything, 'fully blown' illnesses, ticks, parasites and after 4 days he came back into the room and said I need to tell you what we decided you had a really bad reaction to that last COVID shot and then I said I told you that 4 days ago.". Therapeutic measures were not taken as a result of gait inability, full blood count abnormal, illness.  Clinical course: Consumer stated, patient had a very bizarre reaction to her COVID booster shot (Pfizer COVID Vaccine), the first two shots did not bother her. When she got the booster shot, she was hospitalized three times. Initially one day she woke up and she could not walk, it means her husband had to help her to walk. We had to call the ambulance to take her to a hospital. The Doctor said to her, they admitted, the Doctor said to her do you have any idea what's wrong and she said she think she was having a very bizarre reaction to her last COVID shot and he looked to me like he did not say it but he looked at me like you are a 74-year-old woman she was going to believe you. So, he tested me for everything, 'fully blown' illnesses, ticks, parasites and after 4 days he came back into the room and said she need to tell you what we decided you had a really bad reaction to that last COVID shot and then she said she told you that 4 days ago. Patient further stated that she had first two shots and there was not a problem, it was the booster shot. Consumer stated, she does not know if this has anything to do with the reaction or not. But at that point her 'medicare was fine' and she was hospitalized and at that time there were no beds in the hospitals and no blood. Consumer stated, She was hospitalized and had to have blood transfusions. she do not know if the low blood count (further clarifications unknown) was due to the vaccine or not. she just know that it was a part of a 4 week, hospitalization, go home, re-hospitalization, go-home." Hospitalization details. Further stated that she had a breast cancer supposedly from taking Ranitidine, which she do not know if it was true or not and she went and had a surgery upon asking the manufacturer name consumer mentioned as It was some 18 years ago. Patient was taking Letrozole, anticancer medication and  Xarelto because she have two genetic malfunction as my blood 'clots' not 'restored' (further clarifications unknown). she just do not know if these are a part of it or not. But she just have these for years and she did not have any trouble until she got the booster shot (further clarifications unknown). The doctor tested her for everything, 'fully blown' illnesses, ticks, parasites and after 4 days he came back into the room and said she need to tell you what we decided you had a really bad reaction to that last COVID shot and then I said I told you that 4 days ago."  The lot number for bnt162b2 was not provided and will be requested during follow up.