weak; lightheaded; My blood pressure low 80's to 90's over 40's to 50's all thru night; dehydrated prior to this admit; shaking; chills; severe headache; right mid and low back pain; high fever up to 103 degrees; Not able to get out of bed except to get to nearby bathroom; This is a spontaneous report from a contactable nurse (patient). A 74-year-old female patient received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE), first dose at the age of 74-years-old via an unspecified route of administration, administered in arm left on 05Mar2021 15:30 (Batch/Lot Number: EN6200) as single dose for covid-19 immunisation.  Medical history included anal cancer (h/o anal cancers/p chemo & RT2013), hypertension, hypothyroidism and new fe deficiency anemia dx during this admit from an unknown date and unknown if ongoing. The patient's concomitant medications were not reported.  The patient has known allergies to Ampicillin, clindamycin, trilafon, imipramine. The patient reported that 4.5 days after 1st dose of Pfizer vaccine on morning of 10Mar2021 09:00, the patient woke up with shaking chills, severe headache, right mid and low back pain, high fever up to 103 degrees within 1/2 hr of onset and not able to get out of bed except to get to nearby bathroom to use toilet when needed. The patient took Tylenol 500 mg up to 5 doses by 10:00 am of 11Mar2021 when fever would not abate; the patient was weak and lightheaded on an unspecified date and since lived alone called a number to take her to ER. On an unspecified date, her blood pressure was low 80's to 90's over 40's to 50's all thru night and 1000 more mg of Tylenol was given at 4:00 am and fever then lowered to 99 or 100. Full infectious work up negative for bacterial sources including abdominal and pelvic cat scan, abdominal ultrasound, CXR, urine culture, she received 2 1/2 liters of IV fluid and IV Ceftriaxone and Flagyl in ER. In case bacterial cause which was not found including blood cultures, due to her BP still not improved by 5:00 am as she was dehydrated prior to this admit, she was admitted on medicine floor for 2 days. The patient underwent lab tests and procedures which included abdomen scan: unknown result on an unspecified date, blood pressure measurement: low 80's to 90's over 40's to 50's all thru night on an unspecified date; still not improved on an unspecified date, body temperature: high fever up to 103 degrees on 10Mar2021; 99 or 100 on an unspecified date, chest x-ray: unknown result on an unspecified date, culture urine: unknown result on an unspecified date, sars-cov-2 test: negative on 10Mar2021, ultrasound abdomen: unknown result on an unspecified date. Therapeutic measures were taken as a result of the events which included IV, fluids, 1 dose of 2 different IV antibiotics (Ceftriaxone and Flagyl) and Tylenol. The patient was recovering from the events.; Sender's Comments: Based on the current available information and the plausible drug-event temporal association, a possible contributory role of the suspect product BNT162B2 to the development of events cannot be excluded.  The case will be reassessed if additional information becomes available.  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.