A new study has linked the COVID-19 vaccine to heavier menstrual flow and irregular vaginal bleeding in some individuals who no longer menstruate due to using hormonal contraception, menopause, or gender affirmative hormonal treatment.
The study by a team from the University of Illinois and Washington University School of Medicine in St Louis investigated the widely reported link between the Covid-19 vaccine and menstruation via a sample of currently and formerly menstruating people using a web-based survey.
Findings showed that 42% of people with regular menstrual cycles bled more heavily than usual while 44% reported no change after vaccination.
“Among respondents who typically do not menstruate, 71% of people on long-acting reversible contraceptives, 39% of people on gender-affirming hormones, and 66% of post-menopausal people reported breakthrough bleeding”. The study shows.
Participants were asked about their period flow and cycle length and medical history. They were then asked about their experiences of their menstrual cycle after the first and second dose of their COVID-19 vaccines.
Of the participants with a regular menstrual cycle, 42% reported they bled more heavily than usual, while 44% reported no change after being vaccinated.
According to the study, the question of whether and when the particular acute immune challenge of the current SARS-CoV-2 vaccines affects menstrual cycling or menstruation is an emerging one with limitations on study design.
“Vaccine trial protocols do not typically monitor for major adverse events for more than seven days, and additional follow-up communications do not inquire about menstrual cycles or bleeding and as such manufacturers had no way of addressing the extent to which this observation was a coincidence or a potential side effect of the vaccines”.
The researchers hope that Answers derived from “this convenience observational sample” can help shape the narrative around the nature of short-term menstrual changes, help clinicians working with vaccine-hesitant patients, and develop the necessary, on-the-ground data on this new phenomenon to design future prospective, mechanistic studies on the relationship between vaccine immune responses and menstrual repair.