The period when received the booster shot lasted 10 days; Dose received: 3 / dose number=3 on 16Sep2021; Dose received: 3 / dose number=3; Multiple unexpected periods followed, at intervals of 14 days, then 13 days, then 9 days, then 22 days / In short, had five menstrual cycles in the timeframe; This is a spontaneous report from a contactable reporter (consumer or other non-HCP). The reporter is the patient.   A 48-year-old female patient (not pregnant) received bnt162b2 (BNT162B2), administered in arm right, administration date 16Sep2021 at 10:45 (Lot number: FE3592) at the age of 48 years as dose 3 (booster), single for COVID-19 immunisation. Relevant medical history included: "Polycystic ovarian syndrome" (unspecified if ongoing), notes: PCOS; "Hyperthyroidism" (unspecified if ongoing); "Pulmonary bulla" (unspecified if ongoing), notes: Lung bullae; "Penicillin allergy" (unspecified if ongoing), notes: Known allergies: Penicillin; "Shellfish allergy" (unspecified if ongoing), notes: Known allergies: Shellfish and "Iodine allergy" (unspecified if ongoing), notes: Known allergies: Iodine. Concomitant medication included: NAPROXEN. Past drug history included: Bactrim, reaction(s): "Drug allergy", notes: Known allergies: Bactrim and Keflex, reaction(s): "Drug allergy", notes: Known allergies: Keflex. Vaccination history included: BNT162b2 (DOSE 2, SINGLE; Lot Number: EN6205; Anatomical site: Left arm; Administration time: 09:45; Route of administration: Unspecified), administration date: 04Mar2021, when the patient was 48 years old, for COVID-19 immunisation and BNT162b2 (DOSE 1, SINGLE; Lot number: EM9809; Anatomical site: Left arm; Administration time: 10:15; Route of administration: Unspecified), administration date: 11Feb2021, when the patient was 48 years old, for COVID-19 immunisation.  The following information was reported: OFF LABEL USE (non-serious) with onset 16Sep2021 at 10:45, outcome "unknown", described as "Dose received: 3 / dose number=3 on 16Sep2021"; IMMUNISATION (non-serious) with onset 16Sep2021 at 10:45, outcome "unknown", described as "Dose received: 3 / dose number=3"; HEAVY MENSTRUAL BLEEDING (non-serious) with onset 16Sep2021 at 12:00, outcome "unknown", described as "The period when received the booster shot lasted 10 days"; POLYMENORRHOEA (non-serious) with onset an unknown date in 2021, outcome "unknown", described as "Multiple unexpected periods followed, at intervals of 14 days, then 13 days, then 9 days, then 22 days / In short, had five menstrual cycles in the timeframe". The events "The period when received the booster shot lasted 10 days" and "Multiple unexpected periods followed, at intervals of 14 days, then 13 days, then 9 days, then 22 days / In short, had five menstrual cycles in the timeframe" were evaluated at the physician office visit. Relevant laboratory tests and procedures are available in the appropriate section. Therapeutic measures were taken as a result of heavy menstrual bleeding and polymenorrhoea.  Additional information: On 16Sep2021, the patient was on the third day of her menstrual cycle when she had received the Covid-19 booster shot. Her typical period lasts three days during a 28 or 29 day cycle. She normally would have had two cycles in the timeframe. The patient did not receive any other vaccines within four weeks prior to the COVID-19 vaccine. Prior to vaccination, the patient was not diagnosed with COVID-19. Since the vaccination, the patient had not been tested for COVID-19.