Menstrual changes after the COVID-19 vaccination should be investigated, a reproductive specialist has said today.
Dr Victoria Male, of Imperial College London, said although reported changes are short lived, research into this possible adverse reaction must be undertaken.
Writing in The BMJ today, she said changes to periods or unexpected vaginal bleeding are not listed as common side effects of COVID-19 vaccination, but by 2 September 2021 more than 30,000 reports had been made to the UK Medicines and Healthcare Products Regulatory Agency (MHRA) surveillance scheme for adverse drug reactions.
However, periods return to normal in the following cycle and there is no evidence that the COVID-19 vaccination adversely affects fertility, added Dr Male.
She said although the MHRA says its surveillance data does not support a link between changes to menstrual periods and COVID-19 vaccines, it is difficult to come to a firm conclusion due to the way in which data is collected.
The ability to compare rates of menstrual changes in vaccinated versus unvaccinated populations are needed – and the US National Institutes of Health (NIH) has already made $1.67 million available for research into the issue.
Menstrual changes have been reported following both mRNA and adenovirus-vectored vaccines and Dr Male speculates that if there is a connection, it could be an immune response to vaccination, rather than to a specific vaccine component.
If a link between vaccination and menstrual changes is confirmed, it will enable individuals having the vaccine to plan in advance for potentially altered cycles.
In the meantime, doctors should encourage their patients to report any changes to periods or unexpected vaginal bleeding after vaccination to the MHRA’s scheme.
“One important lesson is that the effects of medical interventions on menstruation should not be an afterthought in future research,” she added.
Male V. Menstrual changes following COVID-19 vaccination. BMJ 16 September 2021; doi: 10.1136/bmj.n2211
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