Could man flu be real after all? Sex hormone estrogen protects women against the virus

A study in American Journal of Physiology reports that the female sex hormone estrogen has anti-viral effects against influenza, meaning that women are better equipped to fight the virus than men.

Estrogen prevents the virus from replicating as much as it could, so an infected woman may experience less of the disease — and is less likely to spread it to someone else.

To examine how estrogen affects the flu virus’s ability to replicate, the research team gathered nasal cells from male and female donors. The researchers exposed the cell cultures to the virus and to estrogen. They found that the hormone reduced flu virus replication in nasal cells from women but not men.

Sabra Klein, the study’s lead investigator, said: ‘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.


The findings in this new study support earlier evidence from studies in animals that showed protective effects of estrogen against the flu.

‘Because estrogen levels cycle in pre-menopausal women, it may be difficult to see this protective effect in the general population. But pre-menopausal women on certain kinds of birth control or post-menopausal women on hormone replacement may be better protected during seasonal influenza epidemics.’

Can we trust health advice?
9 February 2016 | 7 p.m. | IET London
Book now