This is a spontaneous report received from a contactable reporter(s) (Physician) from medical information team. An 11-year-old female patient received BNT162b2 (BNT162B2), as dose 1, single (Batch/Lot number: unknown) and as dose 2, single (Batch/Lot number: unknown) for Covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. The following information was reported: TRANSFUSION (hospitalization), outcome "unknown", described as "Patient ended up in the hospital getting a blood transfusion"; DISSEMINATED INTRAVASCULAR COAGULATION (medically significant), INFLAMMATION (non-serious), outcome "unknown" and all described as "Her Uterus is inflamed and its almost like a DIC"; HEAVY MENSTRUAL BLEEDING (non-serious), outcome "unknown", described as "Had Heavy menstrual bleeding"; PRODUCT ADMINISTERED TO PATIENT OF INAPPROPRIATE AGE (non-serious), outcome "unknown", described as "11-year-old Female patient received 2 doses of adult Pfizer BioNTech Covid-19 vaccine". Clinical course: The patient had received her Pfizer BioNTech COVID vaccine at a (facility withheld) where the dose given to her was similar to what her elder sister had received. Caller stated that the patient (11-year-old female) had heavy menstrual bleeding. The changes in her menstrual flow happened after the first dose to a smaller degree and it progressed to extremely heavy bleeding after the second dose of Pfizer BioNTech vaccine.  She would like to know if there is any guideline or treatment recommendations in cases such as her patient as she has encountered this previously. Physician calling about pediatric ages 5-11 Pfizer COVID-19 vaccine who said she saw a patient today who is 11 and received two doses of adult formula COVID-19 vaccine. She said she was trying to figure out if the 5-11 year old vaccine is different than the adult formula, since caller was not sure if what patient was experiencing was dose related, like if it was the same formula and they gave her too much because she was younger or if it was different formula. Caller said she knows the pediatric vial has an orange cap rather than purple or gray. Caller also stated that she had read somewhere that the efficacy of the vaccine was less effective compared to adults and she would like to know, how soon after receiving the vaccine this efficacy would drop as the lower the efficacy the lower the side effects and informed caller that SARS-CoV-2 50 percent neutralizing antibody titers (NT50) 1 month after the primary series for immunogenicity however there was no additional data beyond that 1 month for ages 5-11. The information on the batch/lot number for BNT162b2 has been requested and will be submitted if and when received. Sender's Comments: Based on the information currently available, The casual association between the reported events and suspected vaccine BNT162B2 cannot be completely excluded. 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.