COVID Vaccines Can Cause Small, Temporary Changes in Menstrual Cycles, Study Shows

When the COVID-19 vaccines were first administered, some people who received their shot noticed a change in their menstrual cycles. Now a dataset from a fertility app called Natural Cycles shows vaccinated people did experience a longer cycle, but that change is temporary. Dr. Hugh Taylor, chair of obstetrics, gynecology and reproductive sciences at the Yale School of Medicine, explains what the study shows — and what it doesn't.