since having the booster periods has become longer than usual; this is a spontaneous report received from a contactable reporter(s) (consumer or other non hcp) from the ra. the reporter is the patient. a 33 year-old female patient (not pregnant) received bnt162b2 (comirnaty), administration date jan2022 (batch/lot number: unknown) as dose 3 (booster), single for covid-19 immunisation. patient is not currently breastfeeding. the patient's relevant medical history and concomitant medications were not reported. vaccination history included: bnt162b2 (dose 1, single), administration date: 06jan2021, for covid-19 vaccination, reaction(s): "menstrual irregularity", "menstrual cycle prolonged"; bnt162b2 (dose 2, single), for covid-19 immunisation. the following information was reported: oligomenorrhoea (medically significant), outcome "unknown", described as "since having the booster periods has become longer than usual". no follow-up attempts are possible; information about lot/batch number cannot be obtained. no further information is expected