bleeding breakthrough; irregular periods; menstrual cycle abnormal; this spontaneous report received from a consumer via a regulatory authority (ie-hpra-2022-093024) on 02-mar-2022 and concerned a 34 year old female of unspecified race and ethnicity. the patient's weight was 63.106 kilograms, and height was not reported. no past medical history or concurrent conditions were reported. the patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin, and batch number were not reported, expiry: unknown) dose was not reported, 1 total (first dose), administered on 03-jul-2021 for covid-19 immunisation. the batch number was not reported. the company is unable to perform follow-up to request batch/lot numbers. drug start period was 3 days. no concomitant medications were reported. on 06-jul-2021, the patient experienced bleeding breakthrough, irregular periods, and menstrual cycle abnormal. the action taken with covid-19 vaccine ad26.cov2.s was not applicable. the patient recovered from bleeding breakthrough, irregular periods, and menstrual cycle abnormal. this report was serious (other medically important condition)