A recent study has linked the COVID-19 vaccine to heavier menstrual flow and unexpected vaginal bleeding in some individuals.
Reports of changes to the menstrual cycle indicate they are temporary and short-lived, but women and people who menstruate or have menstruated need reliable information to make informed choices, and hopefully, combat vaccine hesitancy.
Women who received the Covid-19 vaccine experienced heavier bleeding during their periods, a study has revealed.
Researchers have found that almost half of trial participants who were menstruating regularly had heavy flow after the vaccine.
The findings, published in the Journal Science Advances, show that 42 per cent of people with regular menstrual cycles experienced heavier bleeding after vaccination, while 44 per cent reported no change and 14 per cent reported lighter periods.
The researchers shared the survey on Twitter and other social media platforms and then analysed the data analysed collected between April 7, 2021, and June 29, 2021. Nine out of 10 of the 39,129 participants identified as women, while one in 10 participants identified as gender diverse.
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.
They also established that those who did not typically menstruate like people on long-acting contraceptives and post-menopausal women experienced unusual bleeding.
This is contained in one of the largest peer-reviewed studies to date on the effects of Covid-19 vaccines on menstruation. It was carried out by researchers at the University of Illinois at Urbana-Champaign and Washington University School of Medicine in St Louis.
They distributed an online survey in April last year to thousands of people around the world.
The study is a product of more than 39,000 responses collected and analysed from individuals aged 18–80, with the researchers assuring that all the respondents had been fully jabbed with Moderna, Pfizer-BioNTech and Johnson & Johnson vaccines and had not contracted the coronavirus before being vaccinated, at least to the best of their knowledge.