Disturbed menstrual cycle added to the list of side effects against COVID-19 vaccine

In the United States, Katharine Lee and her friend were vaccinated against COVID-19 which resulted in an awkward situation. According to a research fellow in the Division of Public Health Sciences at Washington University in St. Louis, they both started their period soon after they took the vaccine.

“It wasn’t a symptom that was on the list,” she says. “I expected that my arm would be sore, or that I might have a fever or a headache, but this just wasn’t on the list.”

According to Kate Clancy, a menstrual cycle student at the University of Illinois, When Clancy got her vaccination, she also had an unusual period. So she posted on Twitter asking if other people did, too and watched dozens of responses roll in. “It made us want to capture those experiences,” Lee says.

The unusual symptom followed a formal study to collect data concerning issues discussing the relation between the COVID-19 vaccines and the menstrual cycle. It’s not a side effect that clinical trials checked for, and it’s not included on the Centers for Disease Control and Prevention’s vaccine health check-in.

There isn’t much research on how vaccination affects menstruation. But vaccines do stress the immune system, and the menstrual cycle sometimes responds to those types of changes. “The menstrual cycle is really dynamic, and it responds to tons of things,” Lee says.