After Katharine Lee got her COVID-19 vaccine, she noticed an unusual side effect: a heavier period. She shared her observation with a fellow anthropologist, Kathryn Clancy, who had the same reaction. Clancy posted her findings on Twitter and the tweet went viral––apparently, they weren’t alone in this: thousands of people were experiencing similar side effects from the vaccination. The two biological anthropologists went on to launch a research study into the effects the COVID-19 vaccines might have on the menstrual cycle. Early findings: even some people who had aged out of periods, or were on hormone-suppressing drugs, experienced sudden, heavier periods. But this wasn’t one of the side effects that the CDC looked for in its studies. As it turns out: this comes from a long lineage of periods, and people with periods, being overlooked in scientific studies. VICE News digs into the history of how and why scientists have failed to adequately study periods and kept any information they do have away from the people who have them. And how that’s having very real consequences today. Subscribe to VICE News here: http://bit.ly/Subscribe-to-VICE-News Check out VICE News for more: http://vicenews.com/ Follow VICE News here: Facebook: https://www.facebook.com/vicenews Twitter: https://twitter.com/vicenews Tumblr: http://vicenews.tumblr.com/ Instagram: http://instagram.com/vicenews More videos from the VICE network: https://www.fb.com/vicevideo #VICENews #News