Since the beginning of spread of the current Corona virus pandemic (which has caused more deaths in men than women), there have been multiple reports in media about the protective effects of female hormones against viral infections.
Previous scientific studies in animals (mainly mice) have shown that the female sex hormone oestrogen has antiviral effects against the Influenza A virus, commonly known as the flu. In these studies, oestrogen reduced flu virus replication in nasal cells from women but not men. It was also observed that the oestrogens initiated their antiviral effects through oestrogen receptor beta. Receptors are protein structures that molecules bind with to induce cells to respond.
Sex differences in susceptibility to SARS virus in mice parallel those observed in patients and also identify oestrogen receptor signaling as critical for protection in females.
Yet other studies have shown that oestrogens have antiviral properties against HIV, Ebola and hepatitis viruses. It is possible (but not proven) that premenopausal women on certain kinds of birth control pills or post-menopausal women on hormone replacement therapy (HRT) may be better protected during seasonal influenza epidemics.
The suggested mechanisms for this protective effect are - estrogen receptor signaling, some immune-relevant genes responsible for recognising pathogens being encoded on the X chromosome, lifestyle differences between men and women, and finally protective effects of oestrogen on cardiovascular health of women.
It is possible that oestrogen helps the body’s immune system in fighting viral infections like COVID-19. But before we reach a firm conclusion on this, there is plenty more well-designed research needed.