In an article in the BMJ, authors argue that menstrual changes after COVID vaccination are plausible and should be investigated.
Listed common side effects of COVID vaccination include a sore arm, fever, fatigue, and myalgia. However, changes to periods and unexpected vaginal bleeding are not listed, and primary care clinicians and those in the reproductive health field are seeing more and more people who have experienced these events shortly after vaccination.
More than 30 000 reports of these events had been made to the UK;s surveillance scheme for adverse drug reactions by 2 September 2021, across all COVID vaccines currently offered.
Most post-vaccination changes to periods return to normal, and there is no evidence that COVID vaccination adversely affects fertility. In clinical trials, there were similar rates for unintended pregnancies in vaccinated and unvaccinated groups. In fertility clinics, fertility measures and pregnancy rates are similar in vaccinated and unvaccinated patients. The UK’s Medicines and Healthcare Products Regulatory Agency (MHRA) says that there are few reported that
Menstrual changes have been reported after both mRNA and adenovirus vectored COVID vaccines, suggesting that, if there is a connection, it is likely to be a result of the immune response to vaccination rather than a specific vaccine component. Human papillomavirus (HPV) vaccinations have also been associated with menstrual changes. Indeed, the menstrual cycle can be affected by immune activation from various stimuli, including viral infection: one study found about a quarter of menstruating women with COVID experienced menstrual disruption.
Biologically plausible mechanisms linking immune stimulation with menstrual changes include immunological influences on the hormones driving the menstrual cycle or effects mediated by immune cells in the lining of the uterus, which are involved in the cyclical build-up and breakdown of this tissue. Research may also help understand the mechanism.
Though the period changes are short lived, there is need for adequate research. Vaccine hesitancy among young women is largely driven by false claims that COVID vaccines could harm their chances of future pregnancy. Failing to thoroughly investigate reports of menstrual changes after vaccination is likely to fuel these fears. If a link between vaccination and menstrual changes is confirmed, this information will allow people to plan for potentially altered cycles. Clear and trusted information is particularly important for those who rely on being able to predict their menstrual cycles to either achieve or avoid pregnancy.
In terms of management, the Royal College of Obstetricians and Gynaecologists and the MHRA recommend that anyone reporting a change in periods persisting over several cycles, or new vaginal bleeding after the menopause, should be managed according to the usual clinical guidelines for these conditions.
The authors conclude by stating there is an important lesson in that the effects of medical interventions on menstruation should not be an afterthought in future research. In clinical trials, participants are unlikely to report changes to periods unless specifically asked, so in future trials, information about menstrual cycles and other vaginal bleeding should be actively solicited.
Source: The BMJ
