Following a rash of complaints, U.S. health officials say there may be a new side effect associated with the COVID-19 vaccines. Apparently, they can change women's menstrual cycles. The news comes after hundreds of women registered complaints, saying they experienced heavier-than-usual bleeding and longer periods after they were inoculated. "Inflammatory reaction has been noticed with the COVID vaccine," says Dr. Akshat Jain, a hematologist at the Loma Linda University School of Medicine. "That inflammation potentially can modulate estrogen response, which could be the link between certain women having heavy periods after the vaccine." A recent study conducted by the Centers for Disease Control and Prevention found that of the initial 13.7 Americans who were vaccinated, 79 percent of those reporting side effects were women.