After Katherine Lee received her COVID-19 vaccine, she and a colleague talked about their side effects. Because they worked in a medical school, they received their shots early and felt it was a great opportunity to understand the experience.
Although they were expecting pain at the injection site and might get fever, they both noticed a symptom they were not expecting: their menstrual cycle had 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 very flexible and dynamic process and responds to many different things in life, such as stress, physical or mental or immune changes,” said Lee, the postdoctoral scientist in the Department of Public Health at the University of Washington. School of Medicine in St. Louis, told TODAY. “The menstrual cycle is supposed to respond and adapt.”
Lee chatted 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 attributed it to the vaccine or maybe perimenopause.”
She reached out to her high school professor, Kathryn Clancy, head of the Clancy Lab at the University of Illinois, which focuses on research on women’s health. Lee mentions the irregular cycles and Clancy is interested. Then she received her first dose.
” A while after a week after this first dose of Moderna and I’ve never had such a period – not even in my twenties when I had a very 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 survey to do that.
“A lot of people have noticed something, but still haven’t heard of (menstrual changes) as a side effect,” Lee said. “So many things can affect people’s menstrual experiences. So, we just thought if it’s a side effect of … this kind of vaccination, it would be good for people to be prepared. “
Both researchers note that they are pro-vaccine and that they are conducting the 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 so that we can work better on preparing for these side effects,” Clancy explained. ‘If people know, for example, it’s to make you bleed more, they’ll have more booklets with them. ”
Vaccinations and menstruation
Experts say it is unclear whether previous studies on vaccinations from the past have looked at whether it affects menstruation. Clancy said the National Institutes of Health in the 1990s recommended a balanced recruitment for drug trials, that women should be included in studies.
“We make a lot of assumptions about vaccines and side effects based on data that do not represent all bodies,” she said. “There are biological and cultural consequences for all sorts of different phenomena, and we have to do really carefully to study them.”
The mechanisms behind the influence of the COVID-19 vaccines on the uterus are not yet known. Although researchers do not understand how the vaccines – which do not cause COVID-19 – can affect menstruation, they do have some understanding of the effect of menstruation on COVID-19. Research, mostly from China, looked at the relationship.
“There are some studies that show that how the COVID virus actually enters the human cells and that these receptors are found partially in the GIT, kidneys, possibly the uterus, possibly the placenta,” said Dr. Island Jewish Medical Center, TODAY told.
In another study, about 200 women with and without COVID-19 were examined in China: ’20, 25% of them have some kind of change in menstruation, whether the volume or the 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 response it creates through the body,” he said.
Dr. Gloria Bachmann noted that estrogen is involved in COVID-19.
‘Estrogen has an effect on COVID so there is a connection. It’s not a bad relationship, but it could be a relationship that changes over time, ‘OB-GYN and director of the Women’s Health Institute at Rutgers Robert Wood Johnson Medical School said TODAY. “There is no research yet. But I look at it in terms that it could potentially cause a menstrual irregularity that is not dangerous, or one that lasts a long time. ‘
Estrogen often plays a role in difficult periods, early periods, periods that are skipped 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 the changes in the period and are worried. Some people may want to take a pregnancy test, while others 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 any menstrual irregularities to V-Safe, a health study conducted 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 participants simply did not notice them or that this smaller group did not experience them.
“It usually takes a while before any problems related to medication or intervention are known because you need time for enough people to get it and report it,” Bachmann explained. “(If it is rare) it does not get on the radar until there are many people who have undergone the intervention.”
The changes appear to be short-lived. Although the data were not analyzed from the survey, Lee noted that people anecdotally report that their menstrual irregularities last only for the cycles after the shots.
‘These are two doses that will usually end up in different cycles for most people. So you can finally notice the disruption for more than one cycle, ”she said. “We’m pretty sure it’s a very short-lived thing.”
People interested in participating in the research survey can do so here.