on the 4th day very strong pain in the lower abdomen; sudden interruption of the menstrual cycle, on the second day spotting; this is a spontaneous report received from a contactable reporter (consumer) from the regulatory authority-web. regulatory number: it-minisal02-843296. a 50 year-old female patient received bnt162b2 (comirnaty), intramuscular, administered in arm right, administration date 03feb2022 (lot number: fp1972) as dose 2, 0.3 ml, single for covid-19 immunisation. relevant medical history included: "hypothyroidism" (unspecified if ongoing), notes: genetic mutation mthfr c677t. the patient's concomitant medications were not reported. vaccination history included: covid-19 vaccine (dose 1, manufacturer unknown), for covid-19 immunisation. the following information was reported: pain (disability) with onset 07feb2022, outcome "unknown", described as "on the 4th day very strong pain in the lower abdomen"; menstruation irregular (disability) with onset 04feb2022, outcome "unknown", described as "sudden interruption of the menstrual cycle, on the second day spotting". additional information: actions taken (no action taken) - impact on quality of life (10/10) sender's comments: only the date of administration of the 2nd dose was specified following which the reporter detects the communicated event of abrupt interruption of the menstrual cycle and subsequent appearance of severe pain in the lower abdomen no follow-up attempts are possible. no further information is expected.; reporter's comments: hypothyroidism genetic mutation mthfr c677t