Ever had a guy tell you about the “man flu” when he’s sick in bed? Turns out, the common myth that men get sicker than women when exposed to the virus might be true. New findings published in the American Journal of Physiology now suggest that the way estrogen affects women’s immune systems might be the reason the ladies seem to battle the flu virus better than men, Time reports.

Researchers from the John Hopkins Bloomberg School of Public Health and School of Medicine studied cells in a lab dish taken from the nasal passages of men and women. Scientists found that compounds that include estrogen, the female reproductive hormone, were more effective in fighting the flu in cells from women than in cells from men.

As a result, researchers noted there might be something about women’s hormonal physiology that’s valuable in fighting the flu virus. Previously, scientists found that inflammation, one of the main ways the immune system responds to infection, changes in the presence of estrogen. Now researchers want to know for sure if estrogen-related substances could reduce the flu virus’s ability to replicate.

This is why scientists are pushing for a lot more research into this flu-fighter hormonal theory. Only then will we know for sure whether there actually is something to the idea that women have a built-in biological ability to fight the flu.

To read more about some common flu myths and the medical facts behind them, click here.