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COVID-19 vaccination and the risk of abnormal uterine bleeding: A nationwide self-controlled case series study
Na-Young Jeong1, SiHyun Cho2, Eunsun Lim3
1Health Science Convergence Research Institute, Ewha Womans University, Seoul, Republic of Korea.
Insights
COVID-19 vaccination, particularly the first dose, was associated with a slight increase in hospital care for abnormal uterine bleeding (AUB). This risk diminished with subsequent doses, showing no significant increase after the second or third vaccine administration.
Area of Science:
- Reproductive Health
- Vaccinology
- Public Health
Background:
- Abnormal uterine bleeding (AUB) is a common gynecological issue.
- Understanding potential side effects of COVID-19 vaccination is crucial for public health.
- Previous studies have explored various vaccine side effects, but AUB requires specific attention.
Purpose of the Study:
- To investigate the association between COVID-19 vaccination and the risk of abnormal uterine bleeding (AUB) requiring hospital care.
- To analyze the risk of AUB in relation to the number of COVID-19 vaccine doses received.
- To provide data on the safety profile of COVID-19 vaccines concerning gynecological health.
Main Methods:
- A nationwide database in the Republic of Korea combining COVID-19 vaccination records and National Health Insurance Service claims was utilized.
- A self-controlled case series analysis was performed on women aged 16-64 diagnosed with AUB within 180 days of their first vaccine dose.
- Incidence rate ratios (IRRs) were calculated for risk periods (1-14, 1-21, 1-28 days) post-vaccination compared to a baseline period.
Main Results:
- A slight elevation in the risk of AUB requiring hospital care was observed within 14 days post-COVID-19 vaccination (IRR 1.04).
- The risk was notably higher following the first vaccine dose across different risk intervals (e.g., 14-day IRR 1.12).
- No significant increase in AUB risk was detected after the second and third COVID-19 vaccine doses.
Conclusions:
- The first dose of COVID-19 vaccination showed a modest association with increased healthcare utilization for AUB.
- The risk of AUB requiring hospital care diminished with subsequent vaccine doses, with no significant increase observed.
- Findings suggest that while the first dose may be linked to a slight temporary increase in AUB-related healthcare visits, overall risk remains low with continued vaccination.
Objective:
To assess the association between COVID-19 vaccination and the risk of the abnormal uterine bleeding (AUB) specifically focusing on vaginal or uterine bleeding that requires hospital care in women.
Methods:
We used a nationwide database in the Republic of Korea that combined COVID-19 registry data, which contains information on COVID-19 vaccination, with the claims database of the National Health Insurance Service. We included women aged 16-64 who received their first vaccine dose and were newly diagnosed with AUB in inpatient or outpatient settings within 180 days after receiving the first dose. A population-based self-controlled case series analysis was used to estimate the incidence rate ratio (IRR) during the risk periods, including 1-14, 1-21, and 1-28 days after each vaccine dose, compared to the baseline period. The baseline period was defined as the period of 1-180 days following the first vaccine dose, excluding the periods that corresponds to the risk periods. To address the SCCS assumption violation from recurrent nature, only the first event during the observation period was considered.
Results:
Among 83,422 eligible patients, the risk of AUB requiring hospital care within 14 days following COVID-19 vaccination was slightly elevated compared to the baseline period (IRR 1.04, 95 % CI 1.02-1.06). The risk was notably higher after the first dose, regardless of the risk interval (14-day risk period: IRR 1.12, 95 % CI 1.09-1.15; 21-day risk period: IRR 1.08, 95 % CI 1.06-1.10; 28-day risk period: IRR 1.07, 95 % CI 1.05-1.09). No significant increase was observed after the second and third doses.
Conclusion:
This study found a modest increase in healthcare utilization for AUB after the first dose of COVID-19 vaccination. However, this trend diminished with subsequent doses, showing no significantly increased risk. These findings should be interpreted while considering factors that influence healthcare-seeking behavior for unexpected vaginal or uterine bleeding.
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