Gender differences in COVID-19 infection. The estrogen effect on upper and lower airways. Can it help to figure out a treatment?

Epidemiologic evidence from the first large-scale studies suggests that males are more se- verely affected than females by Severe Acute Respiratory Syndrome-CoronaVirus-2 (SARS-CoV-2). They present worse outcomes, require longer hospitalization time and have a higher mortality rate when compared with women. Scientists have speculated that female hormones, especially estrogen, could explain the better outcomes and the higher resistance to the virus observed in women. This higher resistance is due to the systemic and local effect of female hormones on the different cells. In particular, estrogens stimulate the immune system by modulating the function of B cells and improving T-helper 2 cell activity. Based on this evidence, we hypothesize the potential utility of a local nasal spray with low- dose isoflavones from soya (natural estrogen) suspended in a solution with sodium could stimu- late nasal receptor by stopping or reducing the aggressiveness of COVID-19 as already suggested by a previous animal study.