It Turns Out ‘Man Flu’ Might Actually Be Real

A recent study in the American Journal of Physiology suggests that certain estrogen-based compounds can make it harder for flu viruses to infect cells. Estrogen, of course, is a female reproductive hormone so it was no surprise that the estrogen compounds, including drugs that are used to treat breast cancer, worked better against the flu in cells that came from women than those that came from men.

The study didn’t prove that women exposed to the flu were less likely to get sick than men. The researchers, from the Johns Hopkins Bloomberg School of Public Health and School of Medicine, only studied cells, in a lab dish, taken from the nasal passages of men and women. But what it did suggest was that there might be something about the female hormonal physiology that might be worth looking into for new flu fighting strategies.

There’s some precedent for investigating the connection between estrogen and the immune system —studies show that inflammation, one of the immune system’s responses against infection, changes in the presence of estrogen. Women’s inflammatory responses also change during their life course as their levels of estrogen fluctuate before, during and after menopause, and also during pregnancy. So the fact that introducing estrogen-related agents can lower the flu virus’ ability to replicate isn’t entirely out of the question. But that doesn’t mean that we’re ready to declare a female immunity of some sort. More research needs to be done to move the work from the lab dish into human volunteers, and scientists need to understand exactly how the hormone interacts with the immune system in more detail before that can happen.