Deadly coronavirus has proven that women are the stronger sex

Statistics show men are more likely to die from Covid-19 – and it seems that is due to fundamental physical differences between the sexes.

With twice as many men as women dying from Covid-19, the pandemic is proving that “man flu” is not a myth and – when it comes to immunity – women really are the stronger sex.

But having a hyper-vigilant and very aggressive immune system has its ­downsides too – it puts women at greater risk of auto-immune conditions such as multiple sclerosis, rheumatoid arthritis and coeliac disease.

Now, some experts believe these sex-based divides in health and immunity hold the key to conquering not only the coronavirus, but many other health ­challenges too.

X VERSUS Y

When the first figures emerged from China they showed that although ­coronavirus infection rates were almost the same for men and women, two-thirds of those dying were men.

Initially, this was put down to the fact that around 62% of Chinese men have smoked, compared to just 3% of women there.

But this theory began to unravel as similar patterns in Covid-19 deaths emerged in Europe and America, where many more women smoke.

Professor Sarah Hawkes, director of the Centre for Gender and Global Health at University College London, says: “What Covid-19 is throwing into stark relief is that there are differences, but it is ­important to understand the difference between sex and gender – sex is ­biological, while gender relates to socially constructed differences.”

Gender differences in lifestyle factors such as smoking, diet and alcohol consumption explain some of the health disparities between men and women.

But it is biology, ­particularly having two X ­chromosomes, that ensures women really are the fittest when it comes to survival.

Dr Sharon Moalem, an award-winning genetics researcher and best-selling author who has spent decades studying this phenomenon, explains: “X chromosomes contain around 1,000 different genes and many are involved in the immune system.

"But the male Y chromosome has only around 70 genes, which are mostly involved in sperm production.”

As a result, women not only have two different versions of many immune system genes, these genes also work together and swap genetic information.

Dr Moalem explains: “It’s like having a tool-box which has two of every tool; two different size screwdrivers, two different hammers, two sizes of wrench.

“On top of this, female cells work together, side by side. They have the ability to make a tool and share it with their sister cell,” she adds.

Hormones play a part too. Dr Kyle Sue, clinical assistant professor in paediatrics and family medicine at the University of Alberta in Canada, says: “Oestrogen tends to be protective, in that it increases the work the immune system is able to do to fight infection, whereas testosterone seems to do the opposite.”

And these differences mean that men and women are dealt very different hands when it comes to health.

HEAD START

The XX-factor gives females an ­advantage before they are even born. Early miscarriage is more common when women have conceived a boy, while ­pregnancy complications such as ­pre-eclampsia and placental problems are also more common when women are carrying a boy.

 Around 55% of babies born before 32 weeks are boys and this rises to around 60% for very premature babies. Boys who are born prematurely are also more likely to suffer lasting damage such as cerebral palsy and cognitive damage.

One reason for this could be that premature girls have higher levels of catecholamine, a fight-or-flight hormone which primes the body for physical activity.

STRONG FINISH

The most obvious example of female survival superiority is life expectancy. The Office of National Statistics ­calculates that, on average, a toddler will live to be 79.3 years old if they’re a boy, but 82.9 years if they’re a girl.

Similarly, a 65-year-old man can expect to live for another 18.6 years, but a woman the same age will have another 21 years. Only one in five men makes it to their 90th birthday, compared to one in three women.

Danish researchers who studied death records from seven famines and epidemics (including the Irish potato famine) found women “are the life-expectancy champions”.

The statistics revealed they lived longer in every case.

HEART OF THE MATTER

Men have a 29% higher risk of ­developing heart disease and are more likely to have cardiac disease before their 50s. In part this is because of ­lifestyle: they are more likely to be overweight, drink to excess and smoke. But hormones are a factor too.

Until menopause, women are protected by their higher levels of oestrogen, with studies confirming the hormone reduces oxidative stress, blood pressure and fibrosis, as well as improving the elasticity of blood vessels.

Conversely, testosterone appears to increase cardiac risk by suppressing levels of heart-friendly HDL cholesterol.

Yet despite this, men are more likely to survive their first heart attack.

As heart disease is still seen as a “male” problem, women often delay seeking help and, when they do, they are 50% more likely to be misdiagnosed.

Women are also less likely to receive bypass surgery, stents and other procedures. Symptoms vary, too. Men usually report crushing chest pain, while women sometimes describe this as tightness or dismiss it as indigestion.

Women are also more likely to ­experience symptoms such as pain in the arms, nausea and sweating, which are not immediately associated with heart attack.

IMMUNITY OVERDRIVE

Having an aggressive immune system puts women at greater risk of auto-immune disorders.

Multiple sclerosis is three times more common in women than men; for every nine women with lupus, only one man is affected; and, under the age of 50, the incidence of rheumatoid arthritis is four to five times higher in women.

But Dr Moalem says women still have an edge. “Even though women are more likely to be affected by auto-immune conditions, compared to the men who get them, women do much better.

"For instance, one study found men had an average MS Severity Score of 5.11 while for women the average was just 3.02.

BEST SHOT

Studies of vaccines, including the MMR, the BCG for tuberculosis and the combined tetanus diphtheria and pertussis shot show women have a much stronger immune response, which gives them better protection.

A large American study of flu jabs found women got two or three times more protection than men from the same dose.

This super-response means women are also more likely to ­experience side-effects – prompting some experts to argue they should have lower doses.

PAINFUL TRUTHS

Women are more likely to seek help for pain problems and appear to be more susceptible to specific ­problems such as migraine and neuropathic pain.

There is also evidence that men and women feel pain in different ways, which could have important implications for pain relief.

For instance, the diabetes drug metformin blocks pain from nerve damage – but only in men.

Some studies suggest women have a higher pain threshold.

When they have access to self-administered opioids following surgery, men give themselves higher doses – even though studies show women need higher doses of morphine to get the same relief.

BODY OF EVIDENCE

Men have a higher proportion of muscle, so burn more calories.

On average men need 2,500kcal a day, while women need 2,000. Women are more efficient at storing fat and typically have six to 11% more body fat.

It’s an evolutionary ­safeguard to ensure they could conceive and breastfeed when food was scarce.

Because women have more body fat and less water in their bodies, if a man and woman of the same weight drink the same amount of alcohol, the woman has a higher blood alcohol reading.