Some women experiencing changes to menstrual cycle after getting vaccine Some women are experiencing changes to their menstrual cycle after getting the COVID-19 vaccine. Doctors are unsure if it's linked together. (Source: KY3) By Region 8 Newsdesk | April 25, 2021 at 7:26 PM CDT - Updated April 25 at 8:59 PM SPRINGFIELD, Mo. (KAIT/KY3) -Several women said they’ve noticed changes to their menstrual cycle after getting the COVID-19 vaccine. According to a report from content partner KY3, one woman shared her experience, saying she lost between 24-32 ounces of blood in a short amount of time. “The bleeding was so heavy,” Sara Staples said. “I would go to the bathroom, four steps later I’d have to go right back. I mean, 15-18 grams is what the tampon is supposed to absorb. I was doing that four times in 20 minutes.”