The study therefore focused on data from 35,000 participants, free of COVID-19 and women aged 45 to 55 who were excluded from the analysis to avoid bias related to natural menstrual changes associated with perimenopause. Lead author Kathryn Clancy concludes with new evidence supporting the risk of menstrual changes following COVID-19 vaccination:
“Menstruating and even formerly menstruating (postmenopausal) women have experienced unexpected bleeding after receiving a COVID-19 vaccine;
An unexpected effect, which is not part of the effects sought in vaccine trials ”.
- 42.1% of participants reported heavier menstrual flow after receiving the COVID-19 vaccine;
- some experienced this effect during the first 7 days, but the majority rather from the 8th to the 14th day after vaccination;
- 43.6% reported no alteration in their menstrual flow after the vaccine;
- 14.3%, a non-significant change like a bit lighter flow.
- Women who have been pregnant are more likely to report heavier bleeding after vaccination;
- A significant number of postmenopausal women, therefore without menstruation, and on hormonal treatment presented with bleeding after receiving the vaccine;
- more than 70% of participants on hormonal contraception and 38.5% of participants on HRT and under testosteronereport this side effect;
- women who have suffered from endometriosis, menorrhagia, fibroids or other reproductive problems are also more likely to report heavier menstrual flow after vaccination;
Do not neglect this side effect: While the increase in menstrual flow in these participants is generally transient, these unexpected changes remain of concern. Physicians should no longer ignore patients’ concerns, stress the researchers who recall that at the start of vaccination campaigns, their colleagues, despite having heard the first reports of menstrual changes after vaccination, often ignored this side effect , and the complaints of their patients. Yet such unexpected bleeding is also one of the first signs of certain cancers in postmenopausal women and those taking testosterone, so these symptoms should prompt screening for these cancers.
“Any woman experiencing this type of bleeding should consult. It will then be useful to know if there are other causes for this haemorrhage”.
How can a vaccine trigger such changes? The side effect had however already been observed with other vaccines including vaccines against typhoid, hepatitis B and HPV and has already been attributed to an increase in inflammatory pathways linked to the immune system. Fortunately, this already known side effect is usually short-lived, which is why in the vast majority of cases, patients will be quickly reassured.
Avoid the vaccine to avoid this effect? The researchers remind that, despite this side effect, the COVID vaccine retains a positive benefit-risk ratio and that having COVID can not only lead to changes in your rules, but also hospitalization, a long form and severe, and in some cases death.