Women vaccinated with the Pfizer or Moderna COVID-19 vaccines are at higher risk of vaginal bleeding, according to a new study.
One or more doses of the messenger RNA shots increased the risk of the bleeding in women aged 12 to 74, Swedish researchers reported in the study, published on May 3 by the British Medical Journal.
Adjustments to the data resulted in the removal of some of the heightened risks, but even after adjustments, younger women were still more likely to experience bleeding after the first and third doses and older women were more likely to suffer from the issue after the first, second, and third doses.
A number of studies, primarily based on self-reporting of symptoms, have identified menstrual irregularities and bleeding as potential side effects of the Pfizer and Moderna COVID-19 vaccines. People have also filed reports to various reporting systems, such as the U.S. Vaccine Adverse Event Reporting System, and Israeli officials found signs that Pfizer’s vaccine causes menstrual issues.
The Swedish researchers sought to examine the risks among the vaccinated by examining national data that covers every woman aged 12 to 74 in the country. After excluding women who had a history of certain conditions such as menstruation disorders and women living at special care facilities, the study population was 2.94 million. Cases were only included if they were diagnosed at a hospital or another health care facility.
Researchers plugged the data into a model that compared the person-time among the unvaccinated, including individuals who later received a vaccine, to the vaccinated. The top-level results were reported, as were numbers broken down by dose and age group, with the population divided into younger women (aged 12 to 49) and older women (50 to 74).
The study covered Dec. 27, 2020, to Feb. 28, 2022.
Prior to adjustment, women of all ages in the population were found to be at higher risk of vaginal bleeding following vaccination. The younger women were also at a heightened risk of menstrual disturbance, defined as being diagnosed with “absent, scanty and rare menstruation” or “excessive, frequent and irregular menstruation.”
After adjusting for covariates such as marital status and days in the hospital, the risks were removed for some doses and diminished for others.
Adjustments almost entirely removed the menstrual disturbance risk, for example, though women were still found at increased risk within seven days of dose one. The risks of bleeding for the younger women were also reduced, though still present within seven days of doses one and three.
An increased risk of bleeding was still present for older women following the adjustments, with a hazard ratio of 1.28 within seven days of a third shot and 1.25 between eight and 90 days following a third dose.
Hazard ratios of one mean there’s no evidence of a negative effect or benefit, while ratios above one indicate an increased risk of an adverse effect. The adjusted results mean vaccinated older women were about 25 percent more likely to experience the bleeding after a third dose, and about 15 percent more likely after any dose.
The increased risk was seen with both Pfizer and Moderna’s vaccine, according to a stratified analysis of the data.
Pfizer and Moderna did not respond to requests for comment.
Dr. Rickard Ljung of the Swedish Medical Products Agency and his co-authors acknowledged the increased risks among the vaccinated but downplayed the findings.
“We observed weak and inconsistent associations between SARS-CoV-2 vaccination and healthcare contacts for postmenopausal bleeding, and even less consistent for menstrual disturbance, and premenstrual bleeding,” they wrote. SARS-CoV-2 is a name for the COVID-19 virus.
“Extensive adjustment for confounding attenuated most risk estimates. The patterns of association are not consistent with a causal effect. These findings do not provide any substantial support for a causal association between SARS-CoV-2 vaccination and healthcare contacts related to menstrual or bleeding disorders,” the researchers added.
Ljung told The Epoch Times in an email that the increased risk of vaginal bleeding within seven days was “most likely an already prevalent bleeding where the woman got vaccinated before appointment” with a health care professional.
Dr. Shelley Cole, an obstetrician-gynecologist in Texas, told The Epoch Times via email after reviewing the paper: “There was a 26% increase in menstrual disturbances in the 1-7 day timeframe. Yet, they cannot draw any conclusions about a causal relationship with the vaccine? Maybe they need to think just a little bit harder.”
Dr. Harvey Risch, professor emeritus of epidemiology at the Yale School of Public Health, who was also not involved in the research, said that the study did not include enough events “to provide definitive conclusions about increased risks of menstrual disturbances or unexpected menstrual bleeding.”
“Too many variables were examined with respect to risks, in comparison to the limited amount of data. That having been said, the rates of bleeding events do not seem dramatically larger for vaccinated than for unvaccinated women,” Risch told The Epoch Times via email. “However, some caution in interpretation is warranted, because the degree to which menstrual disorders were detected by the medical care system in Sweden during this period is unclear, as the authors note.”
Limitations of the paper included its reliance on observational data. The research received funding from the Swedish government and researchers, including Ljung, reported conflicts of interest such as funding from Pfizer.
From The Epoch Times