A European Medicines Agency (EMA) committee has recommended adding heavy menstrual bleeding to the list of side effect of mRNA COVID-19 vaccines made by Moderna, as well as Pfizer and its partner BioNTech.

Reports of heavy periods – bleeding characterised by increased volume and/or duration that interferes with the quality of life – have been observed during clinical trials, from cases in the real world and in medical literature, the EMA said.

It said that cases of heavy menstrual bleeding have been reported after the first, second and booster doses of Comirnaty and Spikevax.

EMA’s safety committee (PRAC) finalised the assessment of this safety signal after reviewing the available data, including cases reported during clinical trials, cases spontaneously reported in Eudravigilance and findings from the medical literature.

“After reviewing the data, the Committee concluded that there is at least a reasonable possibility that the occurrence of heavy menstrual bleeding is causally associated with these vaccines and therefore recommended the update of the product information,” a statement said.

The available data reviewed involved mostly cases which appeared to be non-serious and temporary in nature.

Any person who experiences postmenopausal bleeding or is concerned about a change in menstruation should consult their doctor, the EMA said.

“There is no evidence to suggest the menstrual disorders experienced by some people have any impact on reproduction and fertility. A review carried out by EMA’s Emergency Task Force showed that mRNA COVID-19 vaccines do not cause pregnancy complications for expectant mothers and their babies,” it added.

Healthcare professionals and patients are encouraged to continue to report cases of heavy menstrual bleeding to their national authorities.