After Katherine Lee received her COVID-19 vaccine, she and a colleague talked about their side effects. Because they worked at a medical school, they received their shots early and felt that this could be a good opportunity to understand the experience.
While expecting pain at the injection site and perhaps getting a fever, they both noticed a symptom they had not expected: their menstrual cycle changed. When Lee started talking to other people who were menstruating, she heard that they also experienced periods that came earlier, felt heavier or just seemed abnormal.
“The menstrual cycle is a really flexible and dynamic process, and it responds to many different things in life such as stress, physical or mental or immune changes,”
Lee spoke informally with colleagues and friends about their periods and some observed differences.
“A number of people said they noticed that their cycles were just a little weird,” she explained. “But maybe it was attributed to the vaccine or maybe it was perimenopause.”
She reached out to her classroom professor, Kathryn Clancy, head of the Clancy Lab at the University of Illinois, which focuses on women’s health research. Lee mentioned the irregular cycles, and Clancy was interested. Then she received her first dose.
“A little after a week after this first dose of Moderna, and I had never had a period that was so heavy – not even in my 20s when I had a really heavy cycle,” Clancy said.
Clancy shared her experience on Twitter and people responded with their own stories. Lee and Clancy realized that they needed to gather this information in a standardized way. So they worked on a study to do just that.
“A lot of people had noticed something but hadn’t heard anything about (menstrual changes) as a side effect,” Lee said. “So many things could affect people’s menstrual experiences. So we just thought that if this is a side effect of … this type of vaccine, it would be good for people to be prepared. “
Both researchers note that they are pro-vaccine and they are conducting research to understand the full range of side effects.
“We need to do more work to notice when there are different effects for different people, really, so we can do a better job of (preparing for) these side effects,” Clancy explained. ex. Know, this is going to make you bleed more, they want more pillows with them. ”
Vaccines and menstruation
Experts say it is unclear whether previous studies of previous vaccines have looked at whether they affect menstruation. Clancy said it was only when the National Institutes of Health recommended a balanced recruitment for drug trials in the 1990s that women should be included in studies.
“We make a lot of assumptions about vaccines and side effects based on data that don’t actually represent all bodies,” she said. “There are biological and cultural effects of all sorts of different phenomena, and we really need to exercise care to study these.”
The mechanisms behind how COVID-19 vaccines can affect the uterus are still unknown at this time. While researchers do not understand how vaccines – which do not cause COVID-19 – can affect menstruation, they do have some understanding of how having COVID-19 affects menstruation. Research, mainly from China, looked at that relationship.
“There are some studies that show how the COVID virus actually enters the human cells, and these receptors are found in part in the GI system, the kidneys, possibly the uterus, possibly the placenta,” Dr. Anar Yukhayev, an OB-GYN for a long time Iceland Jewish Medical Center, told TODAY.
Another study looked at about 200 women with and without COVID-19 in China, who found “about 20, 25% of them have some form of change in their menstruation, whether it’s volume or irregularity,” he said.
Yukhayev wonders if the inflammation that plays a role in the virus is contributing to the changes.
“Maybe not the virus itself, but maybe it’s the antibodies and the inflammatory reaction that it creates throughout the body,” he said.
Dr. Gloria Bachmann noted that estrogen is involved in COVID-19.
“Estrogen has (has a) effect on COVID, so there is a kind of compound. It’s not a bad connection, but it can be a connection that changes a period, “said OB-GYN and director of the Women’s Health Institute at Rutger’s Robert Wood Johnson Medical School TODAY. “There is no research yet. But I look at it in terms it can potentially cause a menstrual irregularity that is not dangerous or one that lasts for a long time. ”
Estrogen often plays a role in heavy periods, early periods, skipped periods or other changes.
“The hormone estrogen is involved in many, if not all, menstrual irregularities,” Bachmann said.
Yukhayev urges people to talk to their doctors if they notice time changes and are concerned. Some people may want to take a pregnancy test, while others may experience a change in menstruation for other reasons, such as fibroids, endometriosis, or polycystic ovary syndrome (PCOS), especially if it lasts longer.
And Bachmann said people should report menstrual irregularities to V-Safe, a health control run by the Centers for Disease Control and Prevention to monitor side effects of COVID-19 vaccines. Menstrual changes were not noticed as possible side effects during clinical trials, but it could be because the participants simply did not notice them or this smaller group did not experience them.
“It usually takes a while before any problems that may be associated with medication or intervention are known because you need some time for enough people to get it and report it,” Bachmann explained. “(If it’s rare) it’s not going on the radar until a lot of people have gotten the intervention.”
Changes appear to be short-lived. While the data have not been analyzed from the study, Lee noted that anecdotally, people have shared that their menstrual irregularities only appear to last in the cycles that follow the shots.
“These are two doses that generally land for most people in different cycles. So you may end up noticing the disturbance for more than one cycle, ”she said. “We’m pretty sure it’s a very short transient thing.”
Individuals interested in participating in the research study can do so here.