diarrhea; nausea; vomiting; then the 2nd dose was ordered and given a week later; This is a spontaneous report received from a contactable reporter(s) (Pharmacist) from medical information team.  A 12 year-old male patient received bnt162b2 (BNT162B2), administered in deltoid left, administration date 05Jan2022 17:00 (Batch/Lot number: unknown) at the age of 12 years as dose 2, 0.3ml single for covid-19 immunisation. Relevant medical history included: "Autism" (unspecified if ongoing), notes: Dates Admitted to autism unit: From: 31Dec2021 To: Unknown, Seriousness criteria :Hospitalization; "Hospitalization" (unspecified if ongoing), notes: Dates Admitted to autism unit:From: 31Dec2021 To: Unknown, Seriousness criteria:Hospitalization. There were no concomitant medications. Vaccination history included: Bnt162b2 (Dose 1, Lot/exp/NDC:UNK), administration date: 28Dec2021, when the patient was 12 years old, for Covid-19 immunization. The following information was reported: INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (non-serious) with onset 05Jan2022 17:00, outcome "unknown", described as "then the 2nd dose was ordered and given a week later"; OVERDOSE (hospitalization, medically significant) with onset 05Jan2022 17:00, outcome "unknown", described as "Received a full adult dose vial"; NAUSEA (hospitalization, medically significant) with onset 10Jan2022, outcome "unknown", described as "nausea"; VOMITING (hospitalization, medically significant) with onset 10Jan2022, outcome "unknown", described as "vomiting"; DIARRHOEA (hospitalization, medically significant), outcome "unknown", described as "diarrhea". Clinical information: case was processed as serious as the patient was prolonged hospitalization, reporter is the pharmacist, and pharmacist called to hospital and states that they discovered yesterday that a 12 year old patient received a fill subsequent dose of the adult formulation Pfizer BioNTech Covid-19 vaccine one week after the first dose. Caller states the 1st dose was given as an outpatient and then the 2nd dose was ordered and given a week later. Caller states the 2nd dose received was supposed to be the 2nd dose to complete the primary series. E-transmitting for a potential duplicate AE. Reporter warm transferred (name-withheld), patient received second dose one week after first dose, Reason for not providing  lot number was Complainant does not have the product with them at the time of call. pharmacist on the line call about the patient received a full dose vial of the Adult BioNTech Covid-19 Vaccine one week after getting the full dose of the vaccine outpatient, The second dose was ordered one week later. reporter confirmed the details are provide, Primary care provider details is unknown to the caller. Primary care provider details were not listed. Patient was in a long term care hospital. Reporter clarified reason for admitted to long term care hospital as, patient was admitted on 31Dec2021 to an autism unit there. When probing for seriousness criteria initially for receiving the second dose one week after the first dose and receiving full adult dose vial caller mentioned it was listed in the chart effects that occurred as nausea, vomiting, and diarrhea, Initially reporter did not see a start date for nausea, vomiting, and diarrhea. However, later saw nausea and vomiting starred 10Jan2022 which was five days later and mentioned so she does not even know if that is a true result from the vaccine. It was just determined last night when the patient's parents came to the facility and provided the patient's vaccination card. The facility was told a different date initially and it was just noticed last night different information had been provided. As a result there was an evaluation by the APRN and there were no abnormalities found. There was no emergency and physician room visit, prior vaccinations was unknown, relevant test was not done, pharmacist confirmed the medication error affected the patient or consumer with clinical consequences, pharmacist confirmed the patient received 0.3mL of correctly prepared vaccine, just at the incorrect interval of a week later. Therefore, this was not a full vial or 5x overdose. Please update previously reported event that describes the overdose, as it was not correctly reported.  The lot number for bnt162b2 was not provided and will be requested during follow up.; Sender's Comments: Based on the Limited information in the case, a contributory effect of the vaccine BNT162B2 to the reported events cannot be ruled out. The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to regulatory authorities, Ethics Committees, and Investigators, as appropriate.