Researchers at the Norwegian Institute of Public Health in Oslo surveyed women who do not menstruate, whether due to perimenopause, menopause, or use of hormonal contraception, who developed vaginal bleeding in the weeks following Covid-19 vaccination. The group followed over 21,000 non-menstruating women as part of a larger group called the Norwegian Mother, Father, and Child Cohort Study. This study was initiated to follow individuals regarding a multitude of health effects of the pandemic, both due to Covid-19 infections as well as any issues related to vaccinations.
The study, published in the September 2023 issue of Science Advances, looked at roughly equal numbers of premenopausal, perimenopausal and postmenopausal women in the group of 21,000 non-menstruating women. They found that there were roughly equal numbers of individuals in each of these groups that experienced vaginal bleeding in the weeks and months following Covid-19 vaccinations. Postmenopausal women reported vaginal bleeding in the four weeks following vaccination two to three times more often than in the weeks prior to vaccination. Bleeding was found three to five times more frequently in the weeks following vaccination in premenopausal and perimenopausal non-menstruating women compared to the weeks following vaccination. The authors discuss and emphasize that this finding should not be considered to be a particular risk or complication of the Covid-19 vaccination. It remains an association, not a cause, and should not be a precluding factor in receiving a Covid-19 vaccination.
A similar study published in 2022 reported that there was an increase in irregular menstrual bleeding following Covid-19 vaccinations in both menstruating and non-menstruating individuals. The investigators discussed several possible reasons to explain this entity, but more importantly emphasized the critical need to engage in focused research in specific demographic populations, without dismissing concerns related to variations in menstrual cycles at any stage of menses.
In the early months of 2021, after the initial roll-out of the first Covid-19 vaccination, women were reporting presence lymph nodes under the armpits, which could be a sign of an advanced form of breast cancer. Many women who underwent either screening or urgent mammograms were experiencing worry, not to mention invasive diagnostic procedures, due to these findings. As I wrote for Forbes, the Society of Breast Imaging issued a statement that women scheduling routine screening mammograms should wait four to six weeks after Covid-19 vaccination before undergoing this exam. They also emphasized that, regardless of vaccine timing, women should not delay evaluation or testing if there are any concerning masses or lumps.
Both the issues of irregular vaginal bleeding and new onset presence of lymph nodes near the breasts underscore the need to better address any medical issues particular to women and underrepresented groups, especially when it comes to large scale health initiatives. Vaginal bleeding in non-menstruating women is often appropriate cause for concern, as it may represent development of a benign or malignant tumor. Irregular bleeding in menstruating women may also be a sign of a benign or malignant tumor, endometriosis, or hormonal irregularities. Abnormal lymph nodes in the breast area of males or females may raise appropriate concerns for a breast malignancy.
Addressing these issues will better identify any particular risk factors, as well as, in the future, lend reassurance that many physiologic events, whether following vaccination or other forms of therapeutics, will be more carefully identified, recognized, and studied.