LONDON (Reuters) - Available data suggest that mRNA COVID-19 vaccines do not cause an absence of menstruation, the European Union's health regulator concluded on Friday.
The assessment was prompted by reports of menstrual disorders after receiving one or two shots of either the Moderna or the Pfizer-BioNTech vaccines.
Menstrual disorders can occur due to a range of reasons, including underlying medical conditions as well as stress and tiredness. Health authorities have highlighted that cases have also been reported following COVID-19 infection.
Absence of menstruation is defined as no bleeding for a period of 90 days or more.
Meanwhile, the European Medicines Agency's Pharmacovigilance Risk Assessment Committee (PRAC) is still investigating cases of heavy menstrual bleeding with the two vaccines.
Reports of heavy periods - bleeding characterised by increased volume and/or duration that interferes with the quality of life - were highlighted as a potential concern after a study in Norway suggested an uptick in instances of the phenomenon following inoculation.
On Friday, the PRAC said it had reviewed all available data on the possible risk but had requested vaccine makers to provide an updated cumulative review of cases.
(Reporting by Natalie Grover in London; Editing by Louise Heavens)