Confusion; Lethargy; tired; Has not been able to mobilize and function; This is a spontaneous report received from a contactable Pharmacist (Patient's Daughter). The 90-year-old male patient (reporters father) received first dose of BNT162B2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE), Lot number: Unknown, via an unspecified route of administration on an unspecified date, as a single dose for COVID-19 immunization. The patient medical history and concomitant medication was not reported.  On an unknown date, the patient started experiencing confusion and lethargy, reported as serious - disabling. He was due to get his second dose of the vaccine on 23Apr2021 and wanted to know if it was safe for him to get the second dose. On 23Apr2021, the pharmacist reported that the patient received the first dose three weeks ago and was due for the second dosage that day, 23Apr2021 at 10 AM. The patient just informed the pharmacist that he had been experiencing side effects from first dosage. The pharmacist stated of course this comes with age, but the patient has had a lot of confusion. Since a week after the shot, the patient had literally not been able to function for the past two and a half weeks. The patient was really concerned if he should get the second shot. The patient reached out to his doctor who didn't know how to advise him because his doctor is not really aware. The doctor was not able to help the patient with what to do. The pharmacist does not know how to advise the patient. The pharmacist clarified that the patient had not been able to function for the past two weeks. Confusion was so bad. The patient was told by the doctor if he missed the second shot, the patient would not be able to get the COVID vaccine anymore. Patient was not feeling good about what he was advised. The patient was lethargic and tired. In the state he was in, the patient was very concerned about getting the second shot. The pharmacist does not know what the patient's doctor meant when stating if patient doesn't get the second shot, patient won't be able to get it anymore. The patient has not been able to mobilize and function, very disabling: Patient was trying to express to the pharmacist that it is very extreme. Patient has not been able to mobilize and function for past two weeks. The patient was really concerned and expressed to the pharmacist that it just hit him. The pharmacist clarified it all hit the patient together at one time. The confusion was staying the same, not getting any better. The lethargic and tired was staying the same, but is to a point where the patient was really concerned. The clinical outcome of the events was not recovered.   No follow-up attempts are needed. Information about lot/batch number cannot be obtained.  Follow-up (23Apr2021): Additional information received from a contactable Pharmacist (Patient's Daughter) included: New events ("tired" and "Has not been able to mobilize and function"), seriousness criteria, outcome, and clinical course details.  Information on the Lot/Batch number has been requested.; Sender's Comments: Based on the information currently available, a possible contributory role of the suspect drug in the reported serious events cannot be completely ruled out given the known suspect drug profile and/or implied temporal association. 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 Regul atory Authorities, Ethics Committees and Investigators, as appropriate.