Study: Estrogen Can Protect Women From The Flu

BALTIMORE, Md. (CBS) – According to a new study, estrogen has anti-viral effects against the flu.

Researchers say a virus infects and causes sickness by entering a cell and making copies of itself inside the host cell. When released from infected cells, the virus can spread through the body and between people. Less replication means the infected person may experience less disease or is less likely to spread the disease to another person.

To examine how estrogen affected the flu virus's ability to replicate, researchers gathered nasal cells from male and female donors. Researchers then exposed the cell cultures to the virus.

The study found that estrogen reduced flu virus replication in nasal cells from women, but not men. Researchers say that the estrogens initiated their antiviral effects through estrogen receptor beta.

Lead investigator of the study, Sabra Klein, PhD, says, "Other studies have shown that estrogens have antiviral properties against HIV, Ebola and hepatitis viruses. What makes our study unique is two-fold. First, we conducted our study using primary cells directly isolated from patients, allowing us to directly identify the sex-specific effect of estrogens. Second, this is the first study to identify the estrogen receptor responsible for the antiviral effects of estrogens, bringing us closer to understanding the mechanisms mediating this conserved antiviral effect of estrogens."

She adds, "Because estrogen levels cycle in premenopausal women, it may be difficult to see this protective effect in the general population, but premenopausal women on certain kinds of birth control or post-menopausal women on hormone replacement may be better protected during seasonal influenza epidemics. We see clinical potential in the finding that therapeutic estrogens that are used for treating infertility and menopause may also protect against the flu."

The study was published in American Journal of Physiology—Lung Cellular and Molecular Physiology.