son is immune compromised; When he got the vaccine he is cognitively more there and she can say look at me and he will do that and that is not his normal.; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP). The reporter is the parent.  A 34-year-old male patient received BNT162b2 (BNT162B2), on 02Jun2022 as dose 3 (booster), 0.3 ml single (Lot number: FM9992, Expiration Date: 30Sep2022) at the age of 34 years, in right arm for covid-19 immunisation. The patient's relevant medical history included: "severe brain injury" (unspecified if ongoing), notes: Her son has a severe brain injury and he is a non verbal adult. There were no concomitant medications. Vaccination history included: BNT162b2 (Covid-19 first vaccine, Date given: 20Jul2021, Manufacturer: Pfizer BioNTech Covid-19, NDC: Unknown, Lot: EW0175, Expiration: Aug2021, Dose given: 0.3 ml, Time given: Around noon, Anatomical location: Right arm), administration date: 20Jul2021, when the patient was 33-year-old, for Covid-19 immunization; BNT162b2 (Covid-19 second vaccine, Date given: 26Aug2021, Manufacturer: Pfizer, NDC: Unknown, Lot: EW0175, Expiration: Aug2021, Dose given: 0.3 ml, Time given: Around noon, Anatomical location: Right arm), administration date: 26Aug2021, when the patient was 33-year-old, for COVID-19 Immunization. The following information was reported: IMMUNODEFICIENCY (medically significant), outcome "unknown", described as "son is immune compromised"; THERAPEUTIC RESPONSE UNEXPECTED (non-serious), outcome "unknown", described as "When he got the vaccine he is cognitively more there and she can say look at me and he will do that and that is not his normal.". Therapeutic measures were not taken as a result of immunodeficiency, therapeutic response unexpected.  Clinical Course: it was reported that the call was about the Covid-19 vaccine. Her son has a severe brain injury and he is a non verbal adult. When he got the vaccine he is cognitively more there and she can say look at me and he will do that and that is not his normal and he just got his third dose at the beginning of June. She said within 24 hours after receiving the vaccine he was brutally aware of things and he will respond and he doesn't normally respond and this last couple a of weeks and is short term. She said she wanted someone to look into that and he may not be the only person gaining cognitive awareness and this could help someone. Even his occupational therapist that comes every Tuesday said he noticed that after each vaccines that (name) is more aware. This is great for people and he is 12 years out from his accident and she is hoping someone would pick up on this. She has been calling since he got the vaccine and someone said to call Pfizer. She said she has called all kinds of people and she even called the Brain institute and this is a recurring thing with every vaccine and this is encouraging to her. The event date. She is not sure of date of first dose but happened within 24 hours after each dose. Her son has the same reaction after each vaccine. He normally struggles to follow simple commands and after vaccines he is pushing for her to ask to do something and it's like he is more there. She confirmed her son received 3 total vaccines. Treatment was None; She said he receives treatment but  not because of the vaccine.  She said she tries experiential stuff on her son so he can participate in this world and it can't hurt him and can only help him go forward and she wants him to go forward. There were no additional Vaccines Administered on Same Date of the Pfizer Suspect If applicable, list all vaccines administered on same date with the Pfizer vaccine considered as suspect. The onset of vaccine was within 24 hours of receiving vaccine. No requirement to visit Emergency Room, Physician Office. There were no vaccinations within 4 weeks prior to the first administration date of the suspect vaccine. The patients Medical History and Family Medical History Relevant to AE and Relevant Tests were none. It was unknown if requested, if a sample of the product available to be returned. It was unknown if packaging sealed and intact.