NIH Awards $1.67M Grants to Probe Potential Links Between COVID-19 Vaccine, Menstrual Changes

A nurse administers a COVID-19 vaccine to a woman at Tableau restaurant in the French Quarter of New Orleans, La., on April 13, 2021. Chris Granger/The Times-Picayune/The New Orleans Advocate via AP

The National Institutes of Health (NIH) on Aug. 30 announced it has awarded one-year supplemental grants totaling $1.67 million to multiple institutions to investigate the potential links between COVID-19 vaccination and menstrual changes.

The announcement comes amid increasing reports among women who claim to have experienced changes to their menstrual cycle after receiving the vaccine. These changes range from irregular or missed menstrual periods to increased bleeding, among others.

In February, Kate Clancy, a medical anthropologist, shared her own experience on Twitter recounting an unusually heavy period after receiving the Moderna vaccine. The post was inundated with responses from others who shared similar accounts.

The NIH’s awards support research to determine whether such changes may be linked to COVID-19 vaccination itself and how long the changes last. Researchers also will seek to clarify the mechanisms underlying potential vaccine-related menstrual changes.

The supplemental grants are awarded to five institutions; Boston University, Harvard Medical School, Johns Hopkins University, Michigan State University and Oregon Health and Science University. The grants are funded by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and the NIH Office of Research on Women’s Health.

Researchers will utilise menstrual tracking applications as well as existing data to evaluate the potential impacts of COVID-19 vaccination on menstrual health among geographically and racially and ethnically diverse populations.

One of the projects will focus specifically on adolescents.

“Researchers will assess the prevalence and severity of post-vaccination changes to menstrual characteristics including flow, cycle length, pain and other symptoms,” NIH said in a statement.

“These analyses will account for other factors that can affect menstruation—such as stress, medications and exercise—to determine whether the changes are attributable to vaccination.”

A healthcare worker prepares a dose of the Johnson & Johnson COVID-19 vaccine during the opening of the MTA's public vaccination program at Grand Central Terminal train station in Manhattan in New York City on May 12, 2021. Carlo Allegri/Reuters

Several projects will also include people who are yet to be vaccinated, and researchers will study the mechanisms underlying the potential effects of COVID-19 vaccines before and after receiving it.

Researchers will examine immune and hormonal characteristics in blood and take tissue and saliva samples from participants before and after they are vaccinated.

NIH noted that multiple factors can cause temporary changes in the menstrual cycle, such as pandemic-related stress, lifestyle changes related to the pandemic, and infection with SARS-CoV-2, the virus that causes COVID-19.

They also noted that immune responses to any of the COVID-19 vaccines could affect the interplay between immune cells and signals in the uterus, leading to temporary changes in the menstrual cycle.

“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 NICHD Director Diana Bianchi.

The researchers hope that their findings will be published by the end of 2022 or soon after, The Seattle Times reports.

Despite anecdotal reports, there is so far no scientific evidence that links COVID-19 vaccines to menstrual irregularities, although the Centers for Disease Control and Prevention (CDC) is not currently conducting further research into the 2,089 incidents of “menstrual irregularity” that have been logged into its Vaccine Adverse Event Reporting System.

“At this time, CDC is not seeing any safety concerns that warrant additional surveillance of irregular menstrual symptoms reported to the Vaccine Adverse Event Reporting System,” Martha Sharan, a public affairs officer for the CDC’s Vaccine Task Force, told The Chicago Tribune.