Does vaccine shedding cause menstrual abnormalities?

A new study, written and widely circulated by anti-vaxxers, suggests that some unvaccinated women reported experiencing menstrual irregularities after being near COVID-19-vaccinated individuals, possibly due to environmental exposure.

The editors of the International Journal of Vaccine Theory, Practice, and Research, the journal publishing this study, include a linguistics Ph.D., a professor of ophthalmology, and several people known for promoting vaccine misinformation. This journal isn’t taken seriously because the people accepting and reviewing papers do not have the background or expertise needed to make good decisions about them.

The study has several critical problems that should make you distrust it. First, it relies on self-reported data from people asked through social media and anti-vaccine groups to provide responses. Everyone in the survey had experienced menstrual abnormalities and had been looking for a cause.

This survey sought to compare the difference between those directly and indirectly exposed to COVID and/or the vaccine. By Spring of 2021, roughly half of all adults in the country had received at least one COVID vaccine, so most people would know or encounter at least one vaccinated person in their lives. So, this study has no proper control group of women who were not exposed to vaccinated people, making it impossible to show that the vaccine was the cause or to see how often symptoms happened.

The most important point is that there’s no clear scientific explanation for how being near vaccinated people could cause menstrual changes. The study mentions “vaccine shedding,” but there’s no proof that mRNA vaccine components can spread this way.

Because of these problems, the study’s results should be viewed with serious doubt and not taken as reliable proof of any connection between being close to vaccinated people and menstrual changes.