The Coronavirus Brief

hen clinical trials began testing COVID-19 vaccines, participants weren’t asked whether their menstrual cycle changed after the shots. But after Initially, some clinicians were dismissive, and chalked up the changes to stress. A survey of 39,000 respondents published in July in the journal however, found that 41% of people with regular periods reported heavier bleeding after vaccination, while 44% said they didn’t notice any change. Older adults, people with reproductive conditions, those using hormonal contraceptives, and nonwhite or Hispanic/Latinx people were especially likely to report this side effect. While changes to periods following a vaccine aren’t unheard-of, the study notes that “attention to these experiences is necessary to build trust in medicine.”