Researchers studying reported menstrual changes after COVID-19 vaccination

BIRMINGHAM, Ala. (WBRC) – Katharine Lee noticed changes in her menstrual cycle not long after getting her COVID-19 vaccine.

“[I reached] out to some of my friends who are also vaccinated to see if they noticed anything,” explained Lee, “because it wasn’t listed as a potential side effect or anything like that.”

One of those friends was Kate Clancy.

“She got her vaccine about a month after I got mine, made that tweet and it took off, with tons of people saying, ‘Yes I noticed this,’ or ‘I thought it was only me,’ or all kinds of responses. It still gets responses today,” said Lee.

The viral response was just the beginning for these friends, who are biological anthropologists.

“We started talking back and forth as that tweet was taking off on that day and I drew up that initial survey and went through some rounds of revisions and got it submitted for ethics approval pretty soon after,” explained Lee, Postdoctoral Research Scholar, Washington University School of Medicine, Division of Public Health Sciences.

“When we were going through ethics approval, Katie and I had a discussion about how many people we anticipated would participate and the number we put in was 500 and that was being optimistic,” said Kate Clancy, PhD, Director of Graduate Studies, Associate Professor of Anthropology, University of Illinois. “We hit 500 I think in the first couple of hours and in fact, were in the thousands within 24 hours.”

Their research survey launched a few weeks ago and has nearly 130,000 replies from women sharing their menstrual experiences after vaccination. Clancy and Lee will use the data collected, “to better understand possible relationships between bleeding patterns and COVID-19 vaccine administration.”

“What we can say, just in broad strokes, is that even in a survey like ours that has selection bias, where probably people with negative experiences, or with menstrual changes are more likely to participate in our study, even with that being the case, it looks like a majority of the respondents did not have menstrual changes after the vaccine,” explained Clancy. “I think that’s the most important thing that we pass on to people. This is a minority who are having this experience. Among those people, just broadly what we can say, is for the most part their experience is that their period is heavier, but we do also see some people with lighter periods, and really the most important finding for us, is not just looking at the experiences of people who are currently menstruating, but looking at people who are not currently menstruating.”

Clancy said women who are on-long active contraceptives or women who are postmenopausal are reporting breakthrough bleeding.

“So, people who have menstruated in the past but are not currently expecting to get a period are getting surprise periods after this vaccine. Those numbers are actually on the higher side, which again indicates this is not a random sample, this is not a perfectly controlled prevalent study, but it does definitely tell us this is happening and in particular, in those populations, there can be some real medical consequences as well as mental health ones because of the surprise of it.”

Lee said she’s heard from many women who said they felt ignored sharing their experiences.

“I think that’s one of the things a lot of people responding to the tweet that Kate did at the beginning of the project kept saying was basically they were surprised, they were worried something went wrong, they were going to their doctor and or they told their family they thought something was different with their period and they were dismissed or really sort of gaslight by clinicians or friends and family and so that’s sort a really common experience that we’re hearing because it’s not listed as a side effect,” said Lee.

“It’s also isn’t listed as a side effect in part because nobody thought to ask about it during the trials, so they only list the trial they expect to happen, or that get reported by a lot of folks who get vaccinated, and this sort of fell between the cracks of the vaccine trials, if it’s a side effect for people in response to the vaccine, it just wasn’t considered during those processes.”

Lee and Clancy recently applied for a grant from the National Institutes of Health to further their research, and hope to publish their initial findings soon.

“We want to make sure we explore it as fully as we can to just bring comfort to people and hopefully encourage them and help them understand that this is not a side effect to be afraid of, this is something that might be uncomfortable but it’s not a reason to, potentially maybe in some really extreme conditions, it is not a reason not to get the vaccine,” said Clancy.

Thousands of women have reported changes in their menstrual cycle trough the Centers for Disease Control and Prevention’s Vaccine Adverse Event Reporting System (VAERS).

WBRC Fox6 reached out to the CDC about those reports and was told, “Many things can affect a woman’s menstrual cycle, including stress-related hormones, changes in schedule, problems with sleep, and changes in diet or exercise. Infections may also impact a person’s menstrual cycle; a recent study from January 2021 documented changes in people’s menstrual cycle related to COVID-19 infection, including a change in flow or cycle length. No studies have been published on changes to a person’s menstrual cycle as a result of COVID-19 vaccination. The Vaccine Adverse Event Reporting System, a vaccine safety system co-managed by CDC and FDA, has received reports of menstrual cycle changes, including heavier periods, early or late onset, and painful cramps. CDC recommends that those concerned about their menstrual cycle or those who have experience any unusual menstrual cycle-related side effects after receiving COVID-19 vaccination, talk to their doctor and share their concerns.”

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