Newswise — Philadelphia (April 1, 2022) – Many people who do not usually menstruate reported experiencing breakthrough bleeding or other period symptoms after receiving a COVID-19 vaccine, according to new findings from an online survey by researchers at Washington University in St. Louis.

The study is the first to examine vaccine-associated breakthrough bleeding in people who take testosterone or other hormones that suppress menstruation. The research focuses on individuals with a range of gender identities such as transgender, nonbinary or gender-fluid. Previous studies of COVID-19 vaccine related menstrual symptoms have largely focused on cisgender (cis) women, those whose gender identity matches the female gender they were assigned at birth. 

“It’s important to examine the impacts of COVID-19 vaccination on menstruation and breakthrough bleeding in people who are not cis women because they are too often left out of the discussion,” said Katharine Lee, PhD, a postdoctoral research scholar in the division of public health sciences at Washington University in St. Louis, first author of the study. “I hope that this study adds to the increasing evidence that maybe we should include periods as part of vaccine research more broadly. Our findings also underscore the importance of including gender-diverse people when we study parts of biology that are closely linked with sex-based reproductive physiology like periods.”

Lee will present the study findings at the American Association for Anatomy annual meeting during the Experimental Biology (EB) 2022 meeting, held in Philadelphia April 2–5. 

Researchers have previously reported that some people with regular or predictable menstrual cycles experience changes in the timing or symptoms of their periods after receiving a COVID-19 vaccine, although these changes are usually temporary and there is no evidence that fertility is affected. For the new study, Lee and colleagues analyzed a subset of responses to an online survey on menstrual experiences after vaccination for insights specific to people who do not usually menstruate.

Out of over 160,000 survey respondents, the researchers identified 552 people who said they used testosterone or other gender-affirming hormones and did not usually menstruate. Most of these respondents (84%) selected more than one gender category, with 460 identifying as transgender, 373 specifying man or man identified, 241 identifying as non-binary and 124 indicating they were genderqueer/gender non-conforming.

One-third of these respondents reported breakthrough bleeding after receiving a COVID-19 vaccine, 9% reported chest or breast soreness and 46% reported having other symptoms they would usually associate with a period, such as cramping and bloating. Some respondents used the survey’s open-ended text boxes to report significant negative mental health impacts in response to their period symptoms, including anxiety, depression, gender dysphoria, panic attacks and suicidal ideation.

Clinical trials for COVID-19 vaccines have not generally examined impacts on menstrual experiences. As a result, these potential effects are not mentioned in the safety information that is provided to vaccine recipients.

“I hope that discussing these findings openly allows people to know that this could be a side effect so they can prepare appropriately,” said Lee. “This is especially important given the fact that some people described mental health outcomes like anxiety, depression and suicidal ideation as responses to unexpected breakthrough bleeding after vaccination.”

Lee added that a better understanding of potential menstrual side effects can help to address the needs of medically underserved populations, including gender-diverse individuals, as well as help reduce vaccine hesitancy. The research team shared results from a different subset of the same survey in a preprint on medRxiv.


Lee will present this research from 11:15 a.m.–12:15 p.m. Monday, April 4, in Exhibit/Poster Hall A-B, Pennsylvania Convention Center (Poster Board Number C118) (abstract). This work will be featured in a virtual press conference from 11–11:45 a.m. EDT on Friday, April 1 (RSVP by Thursday, March 31). Contact the media team for more information or to obtain a free press pass to attend the meeting.






About Experimental Biology 2022

Experimental Biology (EB) is the annual meeting of five scientific societies bringing together thousands of scientists and 25 guest societies in one interdisciplinary community. With a mission to share the newest research findings shaping clinical advances, EB offers an unparalleled opportunity to tap into the latest research in anatomy, biochemistry, molecular biology, investigative pathology, pharmacology and physiology. The Experimental Biology 2022 meeting will be held April 2–5 at the Pennsylvania Convention Center in Philadelphia. #expbio


About the American Association for Anatomy (AAA)

AAA is the professional home for an international community of biomedical researchers and educators focusing on the structural foundation of health and disease. Founded in 1888, the Association advances anatomical science through research, education, and professional development.