From the article:
To examine how estrogen affected the flu virus’s ability to replicate, the research team gathered nasal cells – the cell type that the flu virus primarily infects – from male and female donors. The researchers exposed the cell cultures to the virus, estrogen, the environmental estrogen bisphenol A and selective estrogen receptor modulators (SERM), which are compounds that act like estrogen that are used for hormone therapy.
The researchers found that estrogen, SERM compound raloxifene and bisphenol A reduced flu virus replication in nasal cells from women but not men. They also observed that the estrogens initiated their antiviral effects through estrogen receptor beta. Receptors are protein structures that molecules bind with to induce cells to respond.
According to Klein, “Other studies have shown that estrogens have antiviral properties against HIV, Ebola and hepatitis viruses.”
[…]
“But, premenopausal women on certain kinds of birth control or post-menopausal women on hormone replacement may be better protected during seasonal influenza epidemics,” she says.