Menstruation and the Covid-19 Vaccine: What a Taboo Side Effect Reveals About Medical Research

By Josie West

As people have recieved the Covid-19 vaccine over the past months, hundreds of thousands have noticed changes in their menstrual cycles. Some have reported their periods were much heavier than usual, while others describe intense cramping after receiving the vaccine. These changes have been most commonly reported in people undergoing hormone treatments or in people who no longer get their period (but have experienced “breakthrough bleeding” after getting the vaccine), but they are also prevalent among current menstruators not undergoing hormonal treatment: 28% of menstruators have reported changes in their cycles and 25% have reported changes in the volume of their menstruation. While experts feel that these impacts are ultimately temporary and do not have long-term health consequences, these side effects expose a major gap in biological and medicinal research.

Only now, after thousands of menstruators have reported these side effects, are scientists looking into the relationship between the vaccine and menstruation. This raises a very important question: why was this not looked at during the initial stages of vaccine trials? Unfortunately, according to Dr. Kathryn Clancy, an associate professor at the University of Illinois, and Dr. Katharine Lee, a postdoctoral researcher at Washington University School of Medicine, it is currently not possible to track menstrual cycles in a scientifically accurate and controlled way; observing these patterns would only have been possible during the initial carefully-monitored vaccine trials. This lack of initial observation has delayed doctors’ ability to share information with the public about the vaccine’s safety in regards to fertility.

Scientists like Dr. Clancy and Dr. Lee are fully confident the vaccine does not cause fertility challenges — the endometrium (the lining of the uterus) generates an immune response which thereby makes irregular menstruation patterns perfectly normal after receiving the vaccine — but there are many who remain wary, largely because accurate information has not been readily available. When reputable sources are not accessible, people can often resort to relying on anecdotal evidence, which causes them to jump to (often inaccurate) conclusions. If one person, for example, was to hear that both their mother and sister had irregular menstrual cycles after receiving the vaccine, they could easily be led to believe there was a link between the vaccine and fertility, dissuading them from getting the vaccine. This type of vaccine hesitancy can only be rectified by clear and reliable scientific information showing the vaccine’s impact is limited to menstruation, and it does not affect fertility.

However, it has been very difficult for the Americans to find reliable information: the CDC only added information on their website about fertility and the vaccine after thousands of menstruators had already received it. In the meantime, countless articles were published feeding into the myth that the vaccine could cause infertility, mainly revolving around the claim that the vaccine causes the body to attack a protein in the placenta called syncytin-1 (which has a similar genetic code to a part of the coronavirus’ spike protein). While this theory is inaccurate — the two proteins have wildly different overall constructions, making it essentially impossible to confuse them — a person who lacked extensive scientific knowledge would have no way of knowing that this claim is inaccurate. The lack of easily accessible and reliable information on this issue, coupled with pre-existing vaccine hesitancy, has made vaccinating all Americans an incredibly daunting task.

The pandemic and the vaccine have shown just how dangerous the effects of the stigma surrounding menstruation can be. Not only has this stigma deterred menstruators from sharing their experiences (many only decided to speak up after hearing others were having similar side effects), it prevented vaccine researchers from being able to provide the public with reliable information in a timely manner. It is imperative that we as a society work to eradicate this stigma so we can ensure that everyone can have access to accurate information to make well-informed healthcare decisions.