Headache; Dizziness; Fatigue; Pain at Injection site; Caller said that the vaccine was administered undiluted to a patient.; Caller said that the vaccine was administered undiluted to a patient.; Caller said that the vaccine was administered undiluted to a patient.; This is a spontaneous report received from a contactable reporter(s) (Pharmacist) from medical information team.  A 11 year-old male patient received bnt162b2 (BNT162B2), intramuscular, administered in arm left, administration date 01Feb2022 16:28 (Lot number: FL0007) at the age of 11 years as dose 2 (tris), 0.2 ml single for covid-19 immunization. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Bnt162b2 (1st dose, Anatomical location: Left arm, Route of administration: intramuscular, Lot: FL3198, Time: 16:06), administration date: 10Jan2022, when the patient was 11 years old, for Covid-19 immunization. The following information was reported: OVERDOSE (non-serious), POOR QUALITY PRODUCT ADMINISTERED (non-serious) all with onset 01Feb2022 16:28, outcome "unknown" and all described as "Caller said that the vaccine was administered undiluted to a patient."; PRODUCT PREPARATION ERROR (non-serious) with onset 2022, outcome "unknown", described as "Caller said that the vaccine was administered undiluted to a patient."; HEADACHE (non-serious) with onset 02Feb2022 09:00, outcome "recovered" (Feb2022), described as "Headache"; DIZZINESS (non-serious) with onset 02Feb2022 09:00, outcome "recovered" (Feb2022), described as "Dizziness"; FATIGUE (non-serious) with onset 02Feb2022 09:00, outcome "recovered" (Feb2022), described as "Fatigue"; VACCINATION SITE PAIN (non-serious) with onset 02Feb2022 09:00, outcome "recovered" (Feb2022), described as "Pain at Injection site". Therapeutic measures were not taken as a result of headache, dizziness, fatigue, vaccination site pain.  Additional information: Reporter reported an inappropriate administration for the Pfizer covid-19 vaccine (Pediatric). Reporter said that the vaccine was administered undiluted to a patient and provided the birthdate of the patient which is (DOB), 11 years old, Male. Reporter asked for guidance regarding the medical error and also mentioned that it is the 2nd dose of the patient. Upon follow up: The patient provided information regarding the reported adverse event(s) with the use of the product. The Pfizer product had a causal effect to the adverse. Medication error query: The patient took Pfizer paediatric covid vaccine administered undiluted volume 0.2 ml IM. The stage of medication error was preparation. The diluent was not adjustment to vaccine vial.  The lot number for the vaccine, [BNT162B2] was not provided and will be requested during follow-up.  Follow-up #01 (15Feb2022): This is a follow-up spontaneous report received from a contactable Pharmacist. This Pharmacist reported in response to HCP letter sent to the Pharmacist via follow-up letter.  Updated information: Reporter address, city added, Patient initials added, age at vaccination added, historical details updated, Dosage regimen details updated, new events (headache, dizziness, fatigue, pain at injection site) added, events onset dates updated. Event assessment added.  Additional information was added.  Follow-up attempts are completed. No further information is expected.