sore deltoid muscle; she inadvertently administered 0.3mL of undiluted Pfizer-BioNTech Covid-19 Vaccine (orange cap) to an 81 year old male and an 81 year old female patient; she inadvertently administered 0.3mL of undiluted Pfizer-BioNTech Covid-19 Vaccine (orange cap) to an 81 year old male and an 81 year old female patient; "she inadvertently administered 0.3mL of undiluted Pfizer-BioNTech Covid-19 Vaccine (orange cap) to an 81 year old male and an 81 year old female patient"; This is a spontaneous report received from a contactable reporter(s) (Nurse) from medical information team.  An 81-year-old female patient received BNT162b2 (BNT162B2), as dose 4 (orange cap; booster), 0.3 ml single (Lot number: FL8094, Expiration Date: 31Aug2022) at the age of 81 years, in left arm for covid-19 immunisation. The patient had no relevant medical history. There were no concomitant medications. Vaccination history included: Covid-19 vaccine (DOSE 1; MANUFACTURER UNKNOWN), for Covid-19 immunization; Covid-19 vaccine (DOSE 2; MANUFACTURER UNKNOWN), for Covid-19 immunization; Covid-19 vaccine (DOSE 3 (BOOSTER); MANUFACTURER UNKNOWN), for Covid-19 immunization. The following information was reported: PRODUCT PREPARATION ERROR (non-serious) with onset 20Jul2022, outcome "unknown", described as ""she inadvertently administered 0.3mL of undiluted Pfizer-BioNTech Covid-19 Vaccine (orange cap) to an 81 year old male and an 81 year old female patient""; PRODUCT ADMINISTERED TO PATIENT OF INAPPROPRIATE AGE (non-serious), UNDERDOSE (non-serious) all with onset 20Jul2022, outcome "unknown" and all described as "she inadvertently administered 0.3mL of undiluted Pfizer-BioNTech Covid-19 Vaccine (orange cap) to an 81 year old male and an 81 year old female patient"; MYALGIA (non-serious), outcome "recovered", described as "sore deltoid muscle". Therapeutic measures were not taken as a result of product administered to patient of inappropriate age, underdose, product preparation error.  Additional information: It was reported that, incorrect formulation of the Pfizer COVID 19 Vaccine that was administered to two 81-year-old patients, one male and one female. The two patients were administered an undiluted 0.3mL dose of the Pediatric Formulation of the COVID 19 Vaccine. It was stated that this results in the patients having received 30mcg, so it actually added up to the appropriate amount of the vaccine for the patients. Transferring agent provides the NDC number for the administered vaccines as: 5926710554. Given undiluted dose of the pediatric formulation of the vaccine on the day of reporting. When prompted for specific seriousness criteria it was stated as no. Both of the patients waited for a half of an hour after vaccine administration for monitoring. The patient did not receive any other medication. The patient had no lab tests.Wrong vial was choosen from the vaccine refrigerator. Both patients that received the vaccine had a sore deltoid muscle for a couple days no other reaction conveyed.   Follow-up (29Aug2022): This is a follow up spontaneous report from a contactable Nurse. This Nurse reported in response to HCP letter sent: Updated information included: Reporter details, Dosage regimen, Vaccination Facility details, Event details (new event sore deltoid muscle.; Sender's Comments: Linked Report(s) : US-PFIZER INC-202200991553 Same reporter/ drug/ event for different patient;