fainted; passed out and was unconscious; still kind of feel weak; bruise on both knees; fall; This is a spontaneous report from a contactable registered nurse (patient, Retired RN). An 85-year-old female patient received her 1st dose of BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, lot number: EL8982) at single dose via an unknown route injection in left arm on 23Jan2021 around 08:15 for Covid-19 immunization. Medical history included ongoing blood pressure high which was controlled with medication, allergic to penicillin and acetylsalicylic acid;ascorbic acid (ASPIRIN).  She had lost weight and shrunk according to when she went to the doctor 2 months ago. No other products were taken. No history of all previous immunization with the Pfizer vaccine considered as suspect; no vaccines administered on same date with the Pfizer vaccine considered as suspect. No other vaccinations within four weeks prior to the first administration date of the suspect vaccine, no events following prior vaccinations. No family medical history relevant to the events. Patient passed out on her way home on 23Jan2021 (unknown time). The event required a visit to Emergency room, but not a Physician office. The event clinical course was as follows: She got the first dose of the Covid-19 vaccine on Saturday 23Jan2021. Patient reported that after being monitored at the vaccination site for 20minutes, she left to go catch the bus and fainted before boarding the bus.  She remembered getting on the bus, but did not remember crossing the street. She passed out and was unconscious. An ambulance was called and they took her back to the hospital where she got the vaccine. She was taken by ambulance back to the ER, stayed for half the day, she received IV fluids, and a brain scan due to her fall. She stated that she still feels kind of weak as of 29Jan2021.  She did not know what time it happened, because she lost her sense of time on that day because she did not remember. When she got to the hospital she woke up and wondered where she was because she did not remember what happened. They got an x-ray of her head to see if she had bumped it, but it was negative. She did have a bruise on both knees. They gave her IV fluids, and kept her there for a little while, then sent her home. She called her doctor the next day, but he was busy, so she talked to the nurse. No treatment was recommended, just said to get a lot of rest. She was scheduled for the 2nd dose on 13Feb2021 and was scared to death. Patient verified that she was not admitted to the hospital. Investigation assessment were performed. They hooked her up to the monitor, did an x-ray and a CT scan while at the hospital on 23Jan2021 which were normal (both fine), and gave her IV fluids. Outcome of fainted, fall, passed out and was unconscious was resolved on 23Jan2021. Outcome of kind of feel weak was not resolved. Outcome of the other event was unknown.; Sender's Comments: Considering the temporal association, a causal association between administration of BNT162B2 and the onset of fainted and unconscious cannot be fully excluded.  The underlying history of high blood pressure for this 85 years old patient  might provide an alternative explanation.  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.