off label use; interchange of vaccine products; 10 weeks no period; late period; this is a spontaneous report received from a contactable reporter (consumer) from the regulatory authority. regulatory number: gb-mhra-webcovid-202202140910133320-ov7z5 (agency). other case identifier(s): gb-mhra-adr 26600160 (agency). a female patient received bnt162b2 (comirnaty) (batch/lot number: unknown) as dose 3 (booster), single for covid-19 immunisation. the patient's relevant medical history and concomitant medications were not reported. vaccination history included: covid-19 vaccine astrazeneca (dose 1, single), for covid-19 immunisation; covid-19 vaccine astrazeneca (dose 2, single), for covid-19 immunisation. the following information was reported: off label use (medically significant), outcome "unknown", described as "off label use"; interchange of vaccine products (medically significant), outcome "unknown", described as "interchange of vaccine products"; menstruation delayed (medically significant) with onset 07jan2022, outcome "not recovered", described as "late period"; amenorrhoea (medically significant), outcome "unknown", described as "10 weeks no period". the patient underwent the following laboratory tests and procedures: sars-cov-2 test: negative, notes: no - negative covid-19 test. patient had not tested positive for covid-19 since having the vaccine. patient was not enrolled in clinical trial. no follow-up attempts are possible; information about lot/batch number cannot be obtained. no further information is expected