Covid vaccine: calls grow for research into potential link with menstrual side-effects

A concrete link between the coronavirus vaccine and changes to menstrual cycles is yet to be established, but scientists say they don’t expect any long-term impact on fertility.

Calls have grown for further research into the effect of the coronavirus vaccine on menstrual cycles, with women around the world reporting short-term interruptions and changes to their cycle following vaccination.

Self-reported changes have included post-menopausal women experiencing bleeding, while others have seen late periods and changes to the length of their cycles.

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Currently, changes to menstruation are not listed as a side-effect of Covid vaccination, but anecdotal evidence over the past few weeks has suggested some are experiencing such changes after having the jab.

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Caroline Criado Perez, author of “Invisible Women”, a book exploring how gendered data bias affects women, Tweeted about the issue earlier this week, accusing drug companies of failing to “factor in the menstrual cycle & adequately sex disaggregate their side effects data”.

Her comments were echoed by Dr. Jen Gunter, an obstetrics and gynecology doctor in the US who wrote a recent blog post on the subject.

“Bleeding that is heavy enough to require a trip to the emergency room would be picked up in most vaccine studies, but not an early period, breakthrough bleeding, a heavier period, or a more painful one. This lack of information is maddening,” she wrote

Scientists and researchers are not yet sure whether there is a causal link.

The outpouring of anecdotal evidence regarding menstrual side-effects has led some researchers to begin probing into the issue, while earlier this month, symptom-tracker app ZOE run by researchers at King’s College London said they were monitoring reports of such effects.

Dr Viki Male, a reproductive immunologist at Imperial College London, said there’s not enough evidence currently available to suggest a clear link between coronavirus vaccination and menstrual side-effects.

“We don't yet know if menstrual cycle changes are a side effect of COVID19 vaccination and, if they are, how common they are. Research is being done to find this out”, she said.

“However, it is worth noting that most reports of this are of disruptions for a single month, occasionally two, so this seems to be a short-term effect. We don't expect there to be any impact on fertility since other vaccines, such as HPV and flu, that have short-term effects on the menstrual cycle have been shown not to harm fertility”, she added.

Dr Male encourages anyone noticing an impact on their period following vaccination to report it through the Yellow Card scheme to help researchers build up a better picture of any link.

She added that she hopes lessons will be learned about the importance of accounting for menstrual cycles in future vaccine and medical trials.

“I hope we learn from this and, in the future, make more detailed assessments of how new medicines and vaccines affect the menstrual cycle during clinical trials, so that we can give people this information from the outset”, she said.