More men are dying with the coronavirus than women, statistics show.
Emerging at the end of last year, only the relatively small number of people who have caught the infection and overcome it are thought to have any immunity.
Official data shows that from the start of 2020 to 27 March, 138 men aged 75-to-84 had died with the coronavirus in England and Wales. This is compared to 77 women of the same age.
Among those over 85, 128 of the registered fatalities were male, while 105 were female.
Early research suggests the coronavirus is mild in four out of five cases, however, it can trigger a respiratory disease called COVID-19.
While some blame lifestyle habits for men’s apparent higher risk, experts add it could also be biological.
Coronavirus: Why are more men dying?
When reports emerged suggesting more men were succumbing to the coronavirus in China and Italy, the pandemic’s former epicentres, many pointed the finger at higher rates of smoking.
In 2017, scientists from the Chinese Center for Disease Control and Prevention (CCDC) looked at the tobacco consumption of 100,000 adults.
Nearly two-thirds (62%) of the male participants claimed to have smoked at some point, compared to just 3.4% of the women.
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“Smoking has been considered one of the biggest contributing factors due to the damage to the cilia in the lungs, increasing the risk of any respiratory infection, not merely COVID-19,” said Dr James Gill from Warwick Medical School.
Cilia are microscopic hairs that line the airways, clearing any microbes or debris.
“Whilst smoking is a plausible factor, globally, across various different cultures, where smoking rates do differ, we are still seeing the sustained difference in mortality between men and women,” said Dr Gill.
Men may simply “not look after their bodies as well”, with higher rates of alcohol consumption and obesity.
In 2017, just under a quarter (24%) of men in England claimed their weekly alcohol intake was more than the recommended maximum of 14 units, compared to 11% of women.
When it comes to BMI, 67% of men in England were obese or overweight in 2017, versus 61% of women.
Lifestyle habits aside, women may launch a more robust immune response when exposed to the coronavirus.
“Women may have a more aggressive immune system, meaning a greater resilience to infections”, said Dr Gill.
“The concept of a more aggressive female immune response may also explain why autoimmune diseases, where the body attacks itself, are also more prevalent in women.”
Autoimmune conditions, like rheumatoid arthritis and multiple sclerosis, come about when the immune system mistakenly attacks the body.
Although why women may have a stronger immune system is not completely understood, it could come down to their DNA.
“The immune response throughout life to vaccines and infections is typically more aggressive and more effective in females compared to males,” said Professor Phillip Goulder from the University of Oxford.
“Several factors contribute to this, but these include the fact females have two X chromosomes compared to one in males, and a number of critical immune genes are located on the X chromosome.
“In particular, the protein by which viruses such as coronavirus are sensed is encoded on the X chromosome.
“As a result, this protein is expressed at twice the dose on many immune cells in females compared to males, and the immune response to coronavirus is therefore amplified in females.”
When it comes to a person’s COVID-19 risk, both biological and environmental factors likely come into play.
“Whilst we don’t have a definitive answer on why there is a difference between how men and women respond [to] a COVID-19 infection at the immunological level yet, currently it is a fair assumption there will be a significant interplay between the biology and the environmental facts”, said Dr Gill.
“Ultimately, whether male or female it is not too late to initiate lifestyle factors such as stopping smoking or increasing intake of fruit and vegetables, which may increase your chances of successfully fighting a COVID-19 infection”.
Secretary of health Matt Hancock previously said it is “abundantly clear” smoking “makes the impact of coronavirus worse”.
What is the coronavirus?
The coronavirus is one of seven strains of a virus class that are known to infect humans.
Others trigger everything from the common cold to severe acute respiratory syndrome (Sars), which killed 774 people during its 2002/3 outbreak.
Since the coronavirus outbreak was identified, more than 1.4 million cases have been confirmed worldwide, according to Johns Hopkins University.
Of these cases, over 308,600 are known to have “recovered”.
Globally, the death toll has exceeded 83,400.
The coronavirus mainly spreads face-to-face via infected droplets expelled in a cough or sneeze.
Although most cases are mild, pneumonia can come about if the coronavirus spreads to the air sacs in the lungs.
This causes them to become inflamed and filled with fluid or pus.
The lungs then struggle to draw in air, resulting in reduced oxygen in the bloodstream and a build-up of carbon dioxide.
The coronavirus has no “set” treatment, with most patients naturally fighting off the infection.
Those requiring hospitalisation are given “supportive care”, like ventilation, while their immune system gets to work.