Proof at last that man flu is real
New research has - once again - appeared to prove the existence of the much-contested "man flu".
The study, published by researchers at Johns Hopkins University, suggests the female sex hormone oestrogen could help women combat the virus, leaving men less protected.
Oestrogen, which is found at higher levels in women than in men, was found to reduce the replication of the "influenza A" virus in nasal cells, thereby initiating antiviral effects against the disease.
"A virus infects and causes sickness by entering a cell and making copies of itself inside the host cell," explains lead investigator Sabra Klein.
"When released from infected cells, the virus can spread through the body and between people. How much a virus has replicated determines its severity.
"Less replication of the virus means the infected person may experience less disease," Klein says, "or is less likely to spread the disease to someone else."
Because the female body contains up to 24 times the amount of oestrogen as the male , women seem better equipped to defend themselves against replication of the "influenza A" virus than men.
Previous studies have found high levels of testosterone, the male hormone, can weaken the immune system - suggesting men pulled the short straw when it comes to both hormones and winter germs.
A 2013 study at Stanford University showed high levels of testosterone can weaken a man's immune response to the flu shot compared to women who are vaccinated against the virus.