dose number=3; The vaccine changed my menstrual cycle. It increased the average duration of my period from 6 days to 9 days.; The vaccine changed my menstrual cycle / It also shortened the length of time between my cycles.; This is a spontaneous report received from a non-contactable reporter(s) (Consumer or other non HCP). The reporter is the patient.  A 40 year-old female patient (not pregnant) received bnt162b2 (BNT162B2), administered in arm left, administration date 15Oct2021 (Lot number: 30155BA) at the age of 40 years as dose 3 (booster), single for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Bnt162b2 (Dose Number: 1, Batch/Lot No: ER 8730, Location of injection: Arm Left, The vaccine changed my menstrual cycle. It increased the average duration of my period from 6 days to 9 days. It also shortened the length of time between my cycles), administration date: 25Mar2021, when the patient was 39 years old, for Covid-19 immunization, reaction(s): "The vaccine changed my menstrual cycle. It increased the average duration of my period from 6 days to 9 days.", "The vaccine changed my menstrual cycle. It also shortened the length of time between my cycles"; Bnt162b2 (Dose Number: 2, Batch/Lot No: ER 8730, Location of injection: Arm Left, the vaccine changed my menstrual cycle. It increased the average duration of my period from 6 days to 9 days. It also shortened the length of time between my cycles), administration date: 15Apr2021, when the patient was 39 years old, for Covid-19 immunization, reaction(s): "The vaccine changed my menstrual cycle. It increased the average duration of my period from 6 days to 9 days.", "The vaccine changed my menstrual cycle. It also shortened the length of time between my cycles". The following information was reported: IMMUNISATION (non-serious) with onset 15Oct2021, outcome "unknown", described as "dose number=3"; OLIGOMENORRHOEA (non-serious) with onset 2021, outcome "unknown", described as "The vaccine changed my menstrual cycle. It increased the average duration of my period from 6 days to 9 days."; MENSTRUATION IRREGULAR (non-serious) with onset 2021, outcome "unknown", described as "The vaccine changed my menstrual cycle / It also shortened the length of time between my cycles.". The events "the vaccine changed my menstrual cycle. it increased the average duration of my period from 6 days to 9 days." and "the vaccine changed my menstrual cycle / it also shortened the length of time between my cycles." were evaluated at the physician office visit. Therapeutic measures were not taken as a result of oligomenorrhoea, menstruation irregular. No follow-up attempts are possible. No further information is expected.  Additional information: It was reported that no prolonged hospitalization, no Disabling/Incapacitating, No Congenital anomaly/birth defect. Patient did not receive any other vaccines within 4 weeks prior to the COVID vaccine. Patient was not diagnosed with COVID-19 Prior to vaccination. The patient has not been tested for COVID-19 Since the vaccination.  No follow-up attempts are possible; information about lot/batch number cannot be obtained