Abstract
The objective of this research was to characterize menstrual changes including amount, duration, and frequency among COVID-19 vaccinated and infected women. We conducted an online nationwide questionnaire survey on premenopausal, non-pregnant women over 18 years of age in Israel, querying about any changes in their menstrual patterns after COVID-19 vaccination or infection. In total, 10,319 women responded, of which 7904 met the inclusion criteria. Changes in menstrual patterns following COVID-19 vaccination or infection were reported in 3689/7476 (49.3%) women compared with 202/428 (47.2%) women, respectively, (P = .387). The most commonly described menstrual disturbance was excessive bleeding (heavy, prolonged, or intermenstrual) in both the vaccinated and infected groups, (80.6% versus 81.4%, respectively, P = .720). Among women who experienced abnormal uterine bleeding (AUB), in most cases (61.1%), it occurred between the vaccination and the ensuing menstrual period. Menstrual disturbances were similar in type among the vaccinated and infected women. In conclusion, AUB emerged as a side effect of the BNT162b2 vaccine and a symptom of the COVID-19 infection and was characterized mainly by excessive bleeding. Although the precise incidence could not be determined in this study, the type of bleeding disorder as well as the characterization of risk factors including increasing age and a baseline menstrual pattern of prolonged, frequent, and heavy menses are well defined. The incidence and the long-term consequences of the BNT162b2 vaccine on uterine bleeding warrant further investigation.