This research study is about your experiences with your period or other menstrual bleeding (such as "spotting") and associated symptoms after receiving at least one dose of a vaccine for COVID-19. Side effects are a common and even important element of the vaccine response, and bleeding patterns can be an important way to understand how our immune systems are activated.
Could the COVID-19 vaccines impact menstruation? Experts discuss
The experts hope that understanding this side effect will help people to be better prepared for heavier or earlier menstrual flow after their doses.
After Katharine Lee received her COVID-19 vaccine, she and a colleague chatted about their side effects. Because they worked in a medical school, they received their shots early and felt this might be a good opportunity to understand the experience.
While they expected injection site pain and to maybe spike a fever, they both noticed a symptom that they had not expected: their menstrual cycles changed. As Lee began talking with other people who menstruated, 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 a lot of different things in life like stress, physical or mental or immune changes,” Lee, the post-doctoral scholar in the public health sciences division at the Washington University School of Medicine in St. Louis, told TODAY. “The menstrual cycle is supposed to respond and adapt.”
Lee informally talked to colleagues and friends about their periods and some observed differences.
“A number of people said they noticed their cycles were just a little weird,” she explained. “But attributed it to maybe the vaccine or maybe it was perimenopause.”
She reached out to her grad school 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 Moderna dose and I had never had a period that was so heavy — not even in my 20s when I was having a really heavy cycle,” Clancy said.
Clancy shared her experience on Twitter and people responded with their own stories. Lee and Clancy realized they needed to gather this information in a standardized way. So, they worked on a survey to do just that.
“A lot of people had noticed something but hadn't heard anything about (menstrual changes) being a side effect,” Lee said. “So many things could impact people's menstrual experiences. So, we just thought 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’re conducting the research to understand the full range of side effects.
“We need to do more work noticing when there are different effects for different people, really, so that we can do a better job of (preparing for) these side effects," Clancy explained. "If people know, for instance, this is going to make you bleed more they're going to have more pads with them.”
