sore arm; tired; Rash; Headache for a couple days after the overdose; Felt chilled; patient received "0.3 ml of the undiluted vaccine"; patient received "0.3 ml of the undiluted vaccine"/vaccine was undiluted; This is a spontaneous report from a contactable pharmacist and other healthcare professional via a Pfizer-sponsored program. An 80-year-old female patient received the first dose of BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, solution for injection, lot number: EL324, expiration date: Apr2021), intramuscular in the left arm, on an unspecified date, at 0.3 mL, single for COVID-19 immunization, at the nursing home. Medical history included high blood pressure, rheumatoid arthritis w/ wrist problems, high cholesterol, cataract surgery 7 years ago (2014), colonoscopy and mammogram regularly (unknown results), allergies to sulfa and iodine and arthritis. Concomitant medications included paracetamol (TYLENOL) for arthritis, losartan, nebivolol hydrochloride (BYSTOLIC), atorvastatin, omeprazole, acetylsalicylic acid (ASPIRIN) and nitrofurantoin (NITRO). Historical vaccine included a flu shot received in October (year not provided) for immunization with no adverse event. The pharmacist reported the inadvertent administration of the COVID-19 vaccine to the patient, by a nurse. She stated that the patient received "0.3 ml of the undiluted vaccine" (Failed to ask if it was the patient's first or second dose). The pharmacist asked for recommendations to monitor the patient post-injection. The patient was given 5 times the normal dose (one undiluted vial), vaccine was undiluted. The reporter said that the pharmacy had given 5 times normal dose of the COVID vaccine, undiluted, and reporter wanted to know what was suggested that they do. On 03Feb2021, the pharmacist reported that she was mixing the vials for administration. She stepped away and a nurse pulled an undiluted vial and gave patient 1 dose from undiluted vial with purple top still on. The pharmacist confirmed that the patient received 0.3 mL of undiluted vaccine, not the full vial. The patient's doctor was also there when it happened, and they both stayed with her for about 3 hours after it happened to monitor the patient. The patient had sore arm and felt tired on an unspecified date. Most of her friends felt the same way after getting the Covid vaccine. No other adverse event experienced since then. The pharmacist called to check on her a few times since the overdose and also called Pfizer to ask if the patient should get second dose. On 04Feb2021, it was reported that on an unspecified date, the patient experienced rash, headache for a couple days after the overdose and felt chilled but took Tylenol and was OK after that. The patient recovered from the events rash, headache for a couple days after the overdose and felt chilled on an unspecified date. The outcome of sore arm and fatigue was unknown.  No follow up attempts are possible. No further information is expected.  Follow-up (02Feb2021 and 03Feb2021): This is a follow-up report combining information from duplicate reports 2021032250 and 2021029952. The current and all subsequent information will be reported under manufacturer report number 2021029952. Additionally, new information was received from the same contactable pharmacist includes: suspect drug details (vaccination route and site, vaccination facility type) and event details (new events sore arm and fatigue).  Information on the batch number and lot number has been requested.  Amendment: This follow-up report is being submitted to allow appropriate reporting to health authorities. Additional information received on 04Feb2021 from the same contactable pharmacist includes: medical history (high blood pressure, rheumatoid arthritis, high cholesterol, cataract surgery, colonoscopy, mammogram, allergy to sulfa and iodine, arthritis), historical vaccine, concomitant medications (losartan, Bystolic, atorvastatin, omeprazole, Aspirin, Nitro) and new events (rash, headache and chills).  Information on the lot/batch number has been requested