Overall, it’s clear menstruating people need to be included in clinical trials—the lack of data on the subject means we can’t know for sure one way or another how the vaccine might affect menstruation. For now, those who have received the vaccine can report their symptoms using the CDC’s  Vaccine Adverse Event Reporting System.

But long-term, the solution is including tracking menstruation and documenting menstrual changes as a routine part of clinical trials, according to Lu-Culligan and Epstein. “Like the fevers reported after the vaccines, a transient change in one’s period may not be bad for your overall health or have any lasting effects, but it’s still informative,” they said.

“Menstruation is something we don’t know enough about,” said Dr. Hugh Taylor, chair of the department of obstetrics, gynecology and reproductive sciences at Yale School of Medicine. “It’s an important indicator of a person’s health, like any other bodily function.”