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Story at a glance

  • Studies on adverse effects of COVID-19 vaccinations reveal that women are especially prone.
  • All 19 anaphylactic reactions of the Moderna vaccine reported from December14, 2020-January 18, 2021 were women.
  • 44 out of 47 anaphylactic reactions of the Pfizer & BioNTech vaccine reported from December 14, 2020-January 18, 2021 were women.
  • A study from the CDC last month revealed that 79.1% of side effects reported were from women, despite only 61.2% of distributed vaccines’ recipients were women.
  • Men and women are biochemically different from each other yet are expected to endure the same treatments in healthcare.

Adverse effects of COVID-19 vaccination

Chills, fatigue, vomiting, body aches, axillary adenopathy (swollen lymph nodes), headaches, and anaphylaxis are all adverse reactions reported by recipients of a COVID-19 vaccine, especially after the second dose.

However, the severity of these symptoms seems to be sex dependent as women endure more significant symptoms than men.

Last month, researchers from the CDC found that 79.1% of side effects reported came from women, even though only 61.2% of distributed vaccines’ recipients were women.

Another study revealed that from December 14, 2020-January 18, 2021 there were 19 anaphylactic reactions to the Moderna COVID-19 vaccination, and they were all women. The same study showed that 44 out of 47 anaphylactic reactions to the Pfizer & BioNTech within the same time frame were women.

Axillary adenopathy is another common side effect of COVID-19 vaccination in women. The Society of Breast Imaging now recommends that women wait to get a mammogram until 4-6 weeks after COVID-19 vaccination because of the side effects mimicking breast cancer.

Healthcare’s history of vaccines and women

Women have a 1.5- to 1.7-fold greater risk of developing an adverse drug reaction than men. (1)

A study which observed this factor says that “The reasons for this increased risk are not entirely clear but include gender-related differences in pharmacokinetic, immunological and hormonal factors”. (2)

The pharmacodynamic differences between men and women are apparently obvious in the healthcare field. However, it was not until the 1990’s that women were regularly included in clinical trials for vaccinations and drugs.

This means that the recommended doses for vaccinations are not made for women. Seeing as men were the only subjects in clinical trials, the doses were designed around their experience.

As for the COVID-19 vaccination clinical trials, the side effects were not sufficiently separated by sex, making it hard for researchers to observe the correlation until after the vaccine was rolled out to the public.

It should also be noted that the clinical trials for the COVID-19 vaccination never tested whether lower doses would be effective for women while easing adverse reactions.

Seeing as it is widely known that pharmacology should be approached with gender-related differences in mind, it is becoming clear that there were neglected aspects of COVID-19 vaccine development.

Further Discussion

Changes in mammogram recommendations for women who receive COVID-19 vaccine

Non-vaccine intervention for SARS-CoV-2 could be on its way, mainstream media ignores it

United States mass vaccinations associated with infant/child mortality rates


(1-2) Rademaker, M. Do Women Have More Adverse Drug Reactions?. Am J Clin Dermatol 2, 349–351 (2001).


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