Earlier this year, as Covid-19 vaccines became more widely available, some women and girls took to social media to describe changes in their menstrual cycles after receiving the injections, including irregular cycles, painful periods and heavy bleeding.
Some postmenopausal women shared stories about their period for the first time in years. Many have wondered if vaccines could be the reason.
Now, researchers at five institutions, supported by funding from the National Institutes of Health, will conduct year-long studies to examine any possible link between vaccination and irregular periods, and to help allay concerns that could prevent women to get vaccinated.
The evidence regarding abnormal periods has so far been purely anecdotal. There is no known link between vaccination and changes in menstruation, and public health experts reiterate that vaccines are safe, effective and necessary to end the pandemic.
But the stories underlie a persistent gap in data on women’s reproductive health and menstrual cycles that is not collected in clinical trials, including Covid vaccine trials. There have also been no published scientific studies examining a potential relationship between the two.
“This is an important and neglected problem,” said Dr Hugh Taylor, director of the department of obstetrics, gynecology and reproductive sciences at the Yale School of Medicine, who added that he had heard her own patients talk about differences in their periods after receiving the vaccine.
“A lot of people have irregular periods for all kinds of reasons, so is it really different in people who have been vaccinated, or is it just that when people have it, they link it to the vaccine?”
The research will be undertaken by teams from Boston University, Harvard Medical School, Johns Hopkins University, Michigan State University, and Oregon Health and Science University. The studies will include participants of all ages and backgrounds who have not yet been vaccinated, including those planning to be vaccinated and those who have not, to study their menstrual cycles before and after.
According to doctors, menstrual health can be a reflection of the overall health of women. But they point out that a number of different factors can temporarily affect a woman’s period, including stress, illness, or lifestyle changes. The periods, including the length and course of a menstrual cycle, also vary widely from person to person.