feeling pretty rough/generally didn't feel good; Dizzy; fatigue; This was his third booster dose administered today; This was his third booster dose administered today; given an entire vial of Comirnaty vaccine with no diluent; vaccine overdose; Received Flu Vaccine same day as Pfizer Covid 19 Vaccine; This is a spontaneous report from a contactable Pharmacist via Pfizer-sponsored Program.  A 69-year-old male patient received BNT162B2 on 04Oct2021 at 12:00 (lot number: 31035BA, expiration date: 30Nov2021, NDC number: 59267100001) (at the age of 69-years-old) via unknown route of administration in left arm at dose 3 (booster), single for COVID-19 immunization; influenza vaccine (High Dose Flu Vaccine) (NDC: 70461012103, Lot Number: 312866, Expiry Date: 30Jun2022) on 04Oct2021 for immunization. Medical history included weakened immune system. The concomitant medications were reported as none. Historical vaccines included the first dose of BNT162B2 on 24Feb2021 (Lot Number: EN6198; Expiry Date: 19Feb2022) (at the age of 69-years-old) for COVID-19 immunization; the second dose of BNT162B2 on 24Mar2021 (Lot Number: ER8763; Expiry Date: 01Jul2021) (at the age of 69-years-old) for COVID-19 immunization. Patient was given an entire vial of Comirnaty vaccine with no diluent.  This was his third booster dose administered today on 04Oct2021 around 12 o'clock. He had not experienced any side effects. Patient Received Flu Vaccine same day as Pfizer Covid 19 Vaccine on 04Oct2021. It was reported that the person mixing it hadn't mixed them before so lack of experience and busy pharmacy operation due to also administering flu shots. There was no other vaccinations within four weeks prior to the first administration date of the suspect vaccine. There was no AE following prior vaccinations. There was no Family Medical History Relevant to AE. There was no Relevant Tests. The events did not require a visit to Emergency Room and Physician Office. On further follow up it was reported that the patient had experienced malaise, fatigue and dizziness. The symptoms were worse in the morning but started to improve in the afternoon and he was able to go outside and do some yard work. On 06Oct2021 the pharmacist checked in again and the patient said he was feeling great and the symptoms had resolved. Pharmacist called today 13Oct2021 and the patient said he is still OK and has no problems and has no further concerns. The outcome of the events was unknown and outcome of new events were recovered.  Follow-up (05Oct2021): This is a follow-up spontaneous report from a contactable Pharmacist. This Pharmacist reported in response to HCP letter sent via telephonic follow-up activity which included that: reporter detail updated, RMH weakened immune system updated and clinical data updated.   Follow-up attempts are completed. No further information is expected.  Follow-up (13Oct2021): This is a follow up spontaneous report from a contactable pharmacist. This pharmacist reported in response to HCP telephonic follow up activity which included that: new events(Fatigue, dizziness and malaise) and outcome of new events. All the new clinical information in the narrative has been amended accordingly.  Follow-up (19Oct2021): This is a follow up spontaneous report from a contactable pharmacist. This pharmacist reported in response to HCP telephonic follow up activity which included no new information has been added.  Follow-up (02Nov2021): This follow-up contains no new safety information.  Follow-up attempts are completed. No further information expected.  Follow-up (09Nov2021): This is a follow-up spontaneous report from a contactable other HCP (pharmacy tech). This other HCP reported in response to HCP letter sent to pharmacist via telephonic follow up activity which included that: No new information has been amended.  No follow-up attempts are needed. No further information is expected.  Follow-up (16Nov2021): This is a follow-up spontaneous report from a contactable pharmacist. This pharmacist reported in response to HCP telephonic follow-up activity which included that: No new information has been amended. Follow-up attempts are completed. No further information is expected.  Follow up (23Nov2021): This is a follow up spontaneous report received from a contactable pharmacist. This pharmacist reported in response to HCP letter sent to pharmacist via telephonic follow-up activity which included that:No new AEs reported  No follow-up attempts are needed. No further information is expected.  Follow-up (30Nov2021): This is a follow up spontaneous report from a contactable pharmacist. This pharmacist reported in response to HCP sent via telephonic follow-up activity which included that: No new AEs reported  Follow-up attempts are completed. No further information is expected