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.