NIH is funding studies on possible effects of COVID-19 vaccines on menstruation

The National Institutes of Health (NIH) is funding studies to determine if there is a link between COVID-19 vaccination and changes in women's menstrual cycles.

On Aug. 30, NIH announced that it has awarded $1.67 million worth of one-year supplemental grants to five institutions to conduct these studies.

"Some women have reported experiencing irregular or missing menstrual periods, bleeding that is heavier than usual, and other menstrual changes after receiving COVID-19 vaccines," the federal agency noted. "The new awards support research to determine whether such changes may be linked to COVID-19 vaccination itself and how long the changes last."

The fives institutions conducting the studies are Boston University, Harvard Medical School, Johns Hopkins University, Michigan State University, and Oregon Health and Science University.

"These rigorous scientific studies will improve our understanding of the potential effects of COVID-19 vaccines on menstruation, giving people who menstruate more information about what to expect after vaccination and potentially reducing vaccine hesitancy," said National Institute of Child Health and Human Development (NICHD) Director Diana W. Bianchi.

The NIH said that a variety of factors can change the menstrual cycle temporarily, as it is "regulated by complex interactions between the body's tissues, cells and hormones."

COVID-19 vaccine immune responses may affect how immune cells and signals in the uterus work together, which would lead to temporary menstrual cycle changes, the NIH explained. But other factors for these changes can be infection with SARS-CoV-2, lifestyle changes resulting from the pandemic, and pandemic-related stress.

The studies will test how severe and prevalent post-vaccination changes are to menstrual pain, cycle length, flow, and other symptoms. Other factors to account for include exercise, medications, and stress, to determine if menstrual changes are from the vaccine.

Some studies will look into possible effects that COVID-19 vaccines have on the menstrual cycle by examinig hormonal and immune characteristics in saliva, blood, and tissue samples taken prior to and after vaccination.

There are currently three COVID-19 vaccines available in the U.S., with Pfizer's being the only one with full approval from the Food and Drug Administration (FDA). Both the Moderna and Johnson & Johnson vaccines are available through FDA emergency use authorization.

The Biden administration announced last month that the Department of Health and Human Services (HHS) will require nursing homes to ensure all their healthcare workers are vaccinated in order to continue receiving Medicaid and Medicare funding. The Pentagon is also requiring all military members to get vaccinated against COVID-19.