Do men fare worse with Covid-19?

Death and infection tolls from the Covid-19 pandemic spreading around the world point to men being more likely than women to contract the disease and to suffer severe or critical complications if they do.

Here are some insights from research and experts:

ARE MEN MORE SUSCEPTIBLE TO INFECTION WITH THE NEW CORONAVIRUS?

It looks that way, yes.

In Italy, an analysis of more than 127,700 Covid-19 cases found that 52.9 percent of all infected people were men and 47.1 percent women. Among Italy's first 14,860 deaths, almost 68 percent were men.

A Chinese Center for Disease Control and Prevention report found that in a dataset of 44,672 confirmed cases, there was a 1.1 percent higher Covid-19 fatality rate in men compared to women.

"Evidence is mounting that men are experiencing more severe symptoms and have a higher mortality rate when compared to women," said James Gill, a specialist at Warwick Medical School.

DO WE KNOW WHY?

There are still many outstanding questions around why men are more frequently and harder hit by Covid-19 infection, but health specialists point to a number of possible factors.

These include both behavioural and biological risks:

* Unhealthy habits, smoking, and their impact

Experts say one influence may be that men, in general, don't look after their bodies as well as women do - with lower levels of handwashing and hygiene, and higher levels of smoking, alcohol use, obesity and other unhealthy behaviours.

In many countries, smoking rates are higher among men than women, and smoking is a known risk factor for many other life-threatening conditions such as heart disease, high blood pressure, lung disease and cancer.

The sex differential in smoking is particularly marked in China, where 50 percent of men smoke, compared to 5 percent of women. In Italy, a 2018 analysis found smoking was more common among men than women across all adult age groups.

* Women's "aggressive" immune response

Another factor is the relative strength of the male and female immune responses.

Research shows that immune response throughout life - to everything from vaccines and infections to autoimmune diseases - is typically more aggressive in women than in men. With Covid-19, a respiratory disease caused by a coronavirus, this may be a particularly significant factor.

Philip Goulder, a professor of immunology at Oxford University, says several factors contribute to women having more aggressive immune systems, including that females have two X chromosomes compared to one in males, and that a number of critical immune genes are found on the X chromosome.

"In particular, the protein by which viruses such as coronavirus are sensed is encoded on the X chromosome," Goulder said. That means this protein is expressed at twice the dose on many immune cells in women compared to men, which in turn could well be boosting females' ability to ward off Covid-19.