Vaccination can cause heavy menstrual bleeding in some women.
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What impact of the Covid-19 vaccine on menstruation? The European Medicines Agency (EMA) estimated on Friday October 28 that messenger RNA vaccines against Covid-19 could be the cause of heavy menstrual bleeding that appeared in some women after their vaccination.
These bleeding “can be considered a potential adverse effect of vaccines” from Pfizer and Moderna, according to the conclusion reported by the National Medicines Agency (ANSM). These effects will now be added to the summaries of product characteristics (SPCs) and package leaflets for these two vaccines.
Reported menstrual disorders after vaccination with an mRNA vaccine, ie those from Pfizer/BioNTech and Moderna, have been closely monitored at national and European level since their detection. Multiple testimonies evoked the appearance of disorders after an anti-Covid vaccination, but the health authorities had not yet established a causal link. In July, the women concerned were notably invited by the ANSM to declare them.
Between July and September 2022, 2,952 cases of menstrual disorders were reported with the Comirnaty vaccine (Pfizer/BioNTech), and 515 with the Spikevax vaccine (Moderna). The majority of these declarations were made directly by the patients. Some declarations relate to very earlier events, possibly dating as far back as the spring of 2021.
Reported menstrual disorders are most often “not serious” and transients, specifies the ANSM. In some patients, however, there is a possible persistence of these effects around 6 months. A more precise analysis of these cases is continuing, the agency said.