Women in France who experienced menstrual issues after receiving a Covid vaccination are being invited to declare them via a new online form, with 10,000 reports already received.
A new page on the subject has been added to the Health Ministry website, encouraging women to include as much detail as possible on the declaration form.
A guide (in French) on how best to fill in the form and what to include has also been uploaded.
The details collected are intended to help enable "regional pharmacovigilance centres to carry out their assessment of reported cases in the most efficient way possible".
The drug safety agency ANSM (Agence nationale de sécurité du médicament et des produits de santé) said it has already received more than 10,000 reports on the subject, including 9,381 connected to the Pfizer vaccine, and 1,557 for the Moderna.
However, it has not yet been concluded if there is a link between menstrual problems and these mRNA messenger jabs.
At this stage, it appears that the side effects remain “non-severe”, the ANSM said, and usually present in one of two ways, either abnormal bleeding (such as spotting or a heavier period than normal) or a delayed or absent period.
So far, the data does not explain why or how these issues are happening, it said. However, current hypotheses suggest that they could be due to other vaccine side effects, such as headaches, fever and nausea.
These can sometimes influence hormones, the ANSM said, as can an infection or illness. Significant stress put on the body by the act of vaccination could also disrupt the hypothalamus-pituitary-ovarian axis that regulates the functioning of the menstrual cycle, it said.
It comes after the ANSM said that changes in menstrual cycles could be a “potential” side-effect of receiving the mRNA vaccines, in a study released on July 30, 2021.