Being male is a significant risk factor for severe covid-19 Ezra Acayan/Getty Images
THE concept of “man flu” – the idea that men make too big a deal out of a cold – is an old joke. But when covid-19 arrived, we had to take a serious look at sex differences in how people respond to infections. Being male was a risk factor for experiencing more severe symptoms of the coronavirus: in England during 2020, men were about 60 per cent more likely to die from covid-19 than women. Men are also nearly twice as likely to be diagnosed with tuberculosis and slightly more likely to die from flu. So does your sex put you at an advantage or disadvantage when it comes to immunity?
There may be several reasons for immune sex differences. For one thing, we have discovered in recent years that oestrogen, the main female sex hormone, broadly stimulates immune system activity. The main male equivalent, testosterone, weakens it. But there are other forces at work too.
Sex is governed by DNA, which comes packaged up into 23 pairs of chromosomes. Most women have two X chromosomes, while most men have one X and one Y. To make sure that cells in female bodies don’t have duplicate X chromosome genes in operation, one X is mostly disabled in every cell.
