PhD student Department of Health Convergence, College of Science & Industry Convergence, Ewha Womans University, Seoul, Republic of Korea Seodaemun-gu, Republic of Korea
Background: Public concerns are on the rise, as cases of menstrual cycle disturbances and unexpected menstrual bleeding are reported among women after COVID-19 vaccination.
Objectives: To describe the characteristics of abnormal uterine bleeding (AUB) reports in women after COVID-19 vaccination in Korea.
Methods: We analyzed AUB reports reported from women using a linked database of the COVID-19 Vaccination Management System and the national health insurance claims database. This database included 1,019,767 cases reported as adverse events after the COVID-19 vaccination through medical institutions from February 26, 2021, to September 30, 2022. We analyzed the frequency and characteristics of AUB reports based on vaccination series and vaccine type (mRNA vaccines, viral vector-based vaccines, and recombinant protein-based vaccines). To calculate reporting rates for each vaccine type, we used the number of vaccine doses administered to women as of September 30, 2022, as the denominator. The patients who visited the hospital with AUB after reporting it were identified using claims data to analyze their medical use patterns. The AUB patients were defined as those diagnosed with ICD-10 codes related to AUB, which includes rare, excessive, frequent, and irregular menstruation after the onset of AUB.
Results: A total of 63,053,365 doses of COVID-19 vaccines were administered to women from February 26, 2021, to September 30, 2022. During the same period, 4,205 women reported AUB: 3,883 (92.3%) reported AUB once, 273 (6.5%) reported it twice, 48 (1.1%) reported it three times, and 1 (0.1%) reported it four times. The median age of women who reported AUB after the COVID-19 vaccination was 42 years (interquartile range [IQR] 31–48). Out of the total 4,577 AUB reports, 1,238 (27.1%) were reported following first dose of COVID-19 vaccine, 2,098 (45.8%) after the second dose, 1,180 (25.8%) after the third dose, and 61 (1.3%) after the fourth dose. The median period from the day of vaccination for each dose to onset of AUB was 8 days (IQR=2–31). The reporting rate of AUB per 100,000 doses was 8.4, 1.6, and 5.4 for mRNA vaccine, viral vector-based vaccine, and recombinant protein-based vaccine, respectively. Of women who reported AUB, 3,317 (78.9%) visited the hospital with AUB, and most were diagnosed with abnormal uterine and vaginal bleeding. There were 1,654 (39.3%) patients who visited the hospital more than twice, and the median interval between the visits was 11 days (IQR=4–35).
Conclusions: This study found that a significant number of AUBs were reported following COVID-19 vaccination, and a large percentage of women who reported AUB visited the hospital. Further research is needed to understand the severity of the reported AUB and its potential association with the COVID-19 vaccination.
