Data suggests COVID-19 kills more men than women, but why?
The trend has been observed in many countries including ones where men do not make up the majority of cases. But why does the virus discriminate between genders? Behavioural factors or does genetics have something to do with it?
We know that COVID-19 can be more deadly for older people and people with comorbidities, but now data emerging from various countries are showing that men account for majority of COVID-19 deaths.
The trend can be found in data from various countries like China, France, Germany, Iran, Italy, South Korea, UK and even India. In India, health ministry data said that men made up about three-fourths of both cases and deaths. This trend also shows up in data from countries where men did not make up the majority of cases.
In China, one analysis found a fatality rate of 2.8% in men compared with 1.7% in women. In Italy, men have accounted for 71% of deaths. In Spain, recent data suggests that twice as many men as women have died and in the UK, of the 4,122 deaths registered, 2,523 were men and 1,599 women.
What's the reason behind this?
The scientific community is yet to arrive at a concrete decision on the reasons behind this phenomenon. But experts are of the opinion that multiple behavioural, lifestyle and even bilogical factors might be behind this discriminatory trend.
Early on, smoking was thought to be a likely explanation. In countries like China, where way more men smoke than women do (estimates suggest that nearly 50% of Chinese men smoke comapred to 2% women), it was assumed that underlying lung conditions contribute to men suffering more from a respiratory disease like COVID-19.
Behavioural factors associated to smoking also contributed to this assumption as smokers touch their lips more and may share contaminated cigarettes.
But with more data in hand, there is a growing belief among experts that more fundamental biological factors are also at play than just smoking habits.
In the UK, 16.5% of men smoke compared with 13% of women, so the differences nowhere near as extreme as in China. But even in the UK, men continue to be overrepresented in COVID-19 statistics.
Professor Sabra Klein of Johns Hopkins Bloomberg School of Public Health told The Guardian that "The growing observation of increased mortality in men is holding true across China, Italy, Spain. We’re seeing this across very diverse countries and cultures. When I see that, it makes me think that there must be something universal that’s contributing to this. I don’t think smoking is the leading factor."
Even if we discount the smoking angle, other behavioural factors that differ across genders may also have a role. Some studies have shown that men are less likely to wash their hands frequently, less likely to seek medical care and one study by Reuters even found that that men are more likely to take the coronavirus threat lightly and behave in ways that expose them to the coronavirus. Though these are generalisations, but for entire populations these could be important factors
Previous research, including by Klein, has revealed that men have lower innate antiviral immune responses to a range of infections including hepatitis C and HIV. “Their immune system may not initiate an appropriate response when it initially sees the virus,” Klein said.
Even during the 2003 SARS outbreak, the mortality rate for that outbreak was significantly higher for men. In Hong Kong, 21.9% of males died against 13.2% of females. While the smoking hypothesis is applicable here, too, one study found there was also a higher death rate among male mice infected with the SARS virus.
Hormones can play a role in this too, as estrogen has been shown to increase antiviral responses of immune cells. And many genes that regulate the immune system are encoded on the X chromosome (of which men have one, and women have two) and "so it is possible that some genes involved in the immune response are more active in women than in men," reported The Guardian.