brain fog; Joint pain; Muscle pain; fatigue (could not move)/ Has serious fatigue at times; her blood pressure has been up; sensitive to heat; cannot think; could not move/ Cannot do anything; immunity went down; The initial case was missing the following minimum criteria: unspecified adverse effect. Upon receipt of follow-up information on 19Sep2023, this case now contains all required information to be considered valid.  This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP) from medical information team, Program ID. The reporter is the patient.  A 76-year-old female patient received bnt162b2 (BNT162B2), on 06May2022 as dose 4 (booster), single (Lot number: KK9893) at the age of 74 years, in left arm for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: bnt162b2 (DOSE 1, SINGLE., lot: EL9264), administration date: 29Jan2021, for COVID-19 immunisation; bnt162b2 (DOSE 2, SINGLE, EN6200, Arm Left), administration date: 25Feb2021, for Covid-19 immunization, reaction(s): "Brain fog", "cannot think"; bnt162b2 (DOSE 3 (BOOSTER), SINGLE, lot: 301358H), administration date: 06Oct2021, for Covid-19 immunization. The following information was reported: DECREASED IMMUNE RESPONSIVENESS (non-serious) with onset Jan2023, outcome "recovered" (Feb2023), described as "immunity went down"; ARTHRALGIA (non-serious) with onset Mar2023, outcome "recovering", described as "Joint pain"; MYALGIA (non-serious) with onset Mar2023, outcome "not recovered", described as "Muscle pain"; BRAIN FOG (non-serious) with onset Mar2023, outcome "not recovered"; THINKING ABNORMAL (non-serious) with onset Mar2023, outcome "not recovered", described as "cannot think"; MOVEMENT DISORDER (non-serious) with onset Mar2023, outcome "not recovered", described as "could not move/ Cannot do anything"; FATIGUE (non-serious) with onset Mar2023, outcome "not recovered", described as "fatigue (could not move)/ Has serious fatigue at times"; HYPERTENSION (non-serious) with onset Mar2023, outcome "not recovered", described as "her blood pressure has been up"; HYPERAESTHESIA (non-serious) with onset Mar2023, outcome "not recovered", described as "sensitive to heat". The patient started experiencing this in early Mar2023, had the following reactions of brain fog and could not move which lasted for 36 hours. Cannot do anything and cannot think. Also experienced fatigue and her blood pressure has been up since March, is higher than normal. Is very sensitive to heat and cannot go outside. Last injection was last 06May2022 is having problems that are a reoccurring thing that has come back and is more complicated. Since May2022 she had no problems, no symptoms of any, no fatigue, no brain fog, no any kind of symptoms other than what people do. She hikes, fish, live in country, volunteer and very busy and active person for her age. Started the first week in Jan2023 she had two stressful events that resolved in Feb2023 that her immunity went down. Clarified that she wondered if her immunity went down. Does not know of anything that made her have all these symptoms in Mar2023. Clarified the stressful events as things that happened in life not a side effect. Treatment involved physical therapy and injections for events Joint pain and cannot do anything. Therapeutic measures were not taken for the other events.; Sender's Comments: Linked Report(s) : US-PFIZER INC-202300303658 Same patient, different event, different dose;