Study Confirms Menstrual Irregularities Following COVID Shots

Throughout the debate over the safety of COVID-19 shots, many women have expressed concerns about the relationship between the shots and menstrual cycle irregularities and fertility. In a study published in the journal Frontiers in Immunology, researchers validated the view by these women that there are unsettling menstrual irregularities following receipt of the COVID shots and that differences in the female response to vaccines should be acknowledged and further studied.¹

“Since there is a prominent sex bias in the immune response to infectious diseases in women and men, the role of sex hormones and cortisol becomes important,” the authors stated. “Women exert robust immune response to antigenic encounters via cell-mediated and humoral arms. The inclusion of women in vaccine trials has been marginalized over the years, which resulted in unwanted high dosage administration of vaccines in women.”¹

The authors offered validity to the menstrual cycle as “the fifth vital sign” and an overall gauge of wellbeing for women. The intricate chemistry of various factors and signals can affect the menstrual cycle, inducing changes in intensity and duration of bleeding, length of cycle, accompanying pain, or absence of cycle entirely.

“Although the change in the menstrual pattern after vaccination is not universal, its effect is quite significant,” the authors stated.¹

Heavier and Longer Bleeding and Less Time Between Cycles After COVID Shots

According to regulatory data from the United Kingdom, more than 39,000 suspected cases of menstrual disturbance were reported. An additional study done on a cohort in the United States, more than 2,400 women reported that 55 percent of women receiving Pfizer’s mRNA Comirnaty biologic, 35 percent who received Modern’s mRNA Spikevax, and seven percent who received the Johnson & Johnson’s adenovirus vectored Ad26.COV2.S. underwent changes in their menstrual cycle.¹

An additional Norwegian study on young adult women found “significant disturbance” in the menstrual cycle including heavier bleeding patterns, an increase in the duration of menstruation, and a shortening of the period between two cycles.¹

Several Mechanisms May Explain Menstrual Cycle Changes After COVID Shots

The authors suggest several potential mechanisms of action for the menstrual changes, such as  higher cortisol levels in women and inflammation responses triggered by the COVID shots. Interaction between the immune system and sex hormones has also been proposed as a reason for differences in immune responses by women versus men following receipt of COVID shots.

Some research suggests that because estrogen receptors are widely expressed on various immune cells, such as natural killer cells and T-cells, there is a correlation between estrogen and immunocompetence regulation and higher incidences of autoimmune disorders in women. Because estrogen and progesterone levels vary throughout phases of the menstrual cycle, this can also affect how and to what extent women react to inflammation stimulated by both infections and vaccination.

The authors of the study wrote:

Instances of viral infections…have disclosed that women have a more robust immune response than men. The clinical implication of sex bias toward infectious studies is much needed where a detailed consideration on the account of drug pharmacokinetics in men and women should be addressed.¹

Vaccines that uniquely affect female physiology and menstrual cycles is not a new phenomenon. The human papillomavirus (HPV) vaccine has been associated with reports of ovarian insufficiency, as well as increased follicle stimulating hormone (FSH), amenorrhea, menstrual irregularities, and premature menopause in women. Research studying possible causes behind this association highlight the hyper immune response provoked by the HPV vaccine.¹

Menstrual abnormalities were also observed in Japanese women after the hepatitis B vaccine, with similar disturbances reported in 1913 after typhoid vaccination.¹

Women Not Required to be Included in Clinical Research Until 1993

Prior to 1993, women were largely left out of clinical research studies and there have been  major gaps in scientific knowledge about the effects of vaccination on women. In 1986, a policy that excluded women from clinical research was revisited and revised. In 1993, the U.S. Congress passed a law requiring the inclusion of women in clinical research. Clinical trial data does not often report the intersection of sex and race and data on women of color, in particular, is lacking.²

Martha Gulati, MD, a physician who gives lectures at medical schools about sex differences in heart and cardiology care says that many students tell her they are hearing about these biological differences for the first time with male biology being taught as the “default”. Dr. Gulati states that learning about how female biology is different— from organ systems to hormones and cellular differences— is considered “special interest.”²

Twice As Many Women As Men Suffer Medication Adverse Effects

It was not until nine years ago that the U.S. National Institutes of Health (NIH) instituted a policy that requires researchers with NIH funding to collect data on biological sex differences in preclinical research and animal testing and report on these differences. Many animal studies avoid female inclusion when possible due to greater costs associated with purchasing and housing both male and female mice, and concerns that the fluctuating hormones and reproductive systems of female mice might confound the study results.²

Failure to acknowledge differences between males and females and study the effects of medications and other medical interventions on women has contributed to women experiencing adverse effects from medications at twice the rate of men.²

One study found that women ages 18-64 generated antibodies “vigorously” against the influenza vaccine and that women’s reactions to just a half dose of the flu vaccine “was equivalent to the reaction of men who received a full dose.” Yet the recommendations for vaccines and doses are the same for men and women without consideration for the gender differences in responses to vaccination.²

Because women’s concerns about health issues are often ignored or minimized, concerns about infertility and menstrual changes associated with the COVID shots were no different and were largely designated as misinformation by the media and health professionals.

Voicing Concerns About Menstrual Cycle Changes Often Labeled “Dramatic Misinformation”

An article written by Science Direct is an example of how women are gaslighted when they talk about personal experiences with changes to their menstrual cycles after getting vaccinated, a reflection of ignorance about the biological effects of vaccination on women and bias against the jmportance of anecdotal evidence as a red flag. The authors of the Science Direct article stated that refuting and correcting misleading claims is a difficult task as individuals recall “dramatic misinformation more readily than science-based factual information that counters it.”³

A 2021 New York Times article stated: “So far, there’s no data linking the vaccines to changes in menstruation. Even if there is a connection, one unusual period is no cause for alarm.”⁴ While many researchers firmly believe there is little to no proof of a causal connection and menstrual dysregulation and COVID shots, other researchers have stressed that women are indeed biologically different than men, that there are valid concerns about how COVID shots affect menstrual cycles, and that these changes should be taken seriously and thoroughly investigated rather than prematurely dismissed.

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