Women's Health

NIH orders $1.67M study on how COVID-19 vaccine impacts menstrual cycle

The National Institutes of Health has announced a $1.67 million study to investigate reports that suggest the COVID-19 vaccine may come with an unexpected impact on reproductive health.

It’s been a little over six months since the three COVID-19 vaccines in the US — Pfizer, Moderna and Johnson & Johnson — became widely available to all adults. But even in the early days of vaccine rollout, some women were noticing irregular periods following their shots, as reported first by the Lily in April.

Shana Clauson, 45, spoke to the Washington Post’s women’s news site at the time, and again this week, about her experience after getting the jab — revealing that her period arrived earlier and heavier than what she considers normal. She was one of many who gathered on social media to share what they were seeing.

woman taking vaccine
The National Institutes of Health will spend $1.67 million to investigate a possible hidden link between the COVID-19 vaccine and reproductive health as some report irregular periods following vaccination.Europa Press via Getty Images

“Is this not being discussed, or is it even being looked at or researched because it’s a ‘woman’s issue?’ ” Clauson speculated to the Lily last spring.

It would appear that the NIH heard Clauson and others’ reports, as they announced on Aug. 30 that they intended to embark on just such research — aiming to incorporate up to half a million participants, including teens and transgender and nonbinary people.

Researchers at Boston University, Harvard Medical School, Johns Hopkins University, Michigan State University and Oregon Health and Science University have been enlisted to embark on the study, commissioned by the NIH’s National Institute of Child Health and Human Development (NICHD) and the Office of Research on Women’s Health.

The approximately yearlong study will follow initially unvaccinated participants to observe changes that occur following each dose. More specifically, some groups will exclude participants on birth control or gender-affirming hormones, which may have their own impact on periods.

“Our goal is to provide menstruating people with information, mainly as to what to expect, because I think that was the biggest issue: Nobody expected it to affect the menstrual system, because the information wasn’t being collected in the early vaccine studies,” said NICHD director Diana Bianchi in a statement to the Lily — reportedly crediting their early coverage for helping to make the NIH aware.

‘We were worried this was contributing to vaccine hesitancy in reproductive-age women.’

NICHD director Diana Bianchi

The NIH suggests that changes to the menstrual cycle could arise out of several of life’s circumstances during a pandemic — the stress of lifestyle changes or possibly contending with illness. Moreover, the immune and reproductive systems are intrinsically linked, and the notion that the immune-boosting vaccine may disrupt the typical menstrual cycle is plausible, as demonstrated by previous studies concerning vaccine uptake.

It’s also worth noting the vaccine does not cause infertility and the Centers for Disease Control and Prevention recommends the shot even for pregnant women.

As changes to the menstrual cycle are “really not a life and death issue,” explained Bianchi, the Food and Drug Administration — fast-tracking their work — prioritized only the most critical risks associated with the COVID-19 vaccine.

The NIH, too, pulled together the initiative at breakneck speed. Funding for such a study would typically take years to see approval.

“We were worried this was contributing to vaccine hesitancy in reproductive-age women,” said Bianchi.