Men are dying from the coronavirus at higher rates than women around the world. Here are scientists' best ideas as to why.

Scientists have a few ideas about why that is some are behavioral, such as that men have higher rates of smoking and worse hygiene on average than women.
Many men also have higher rates of underlying preexisting conditions , such as high blood pressure and diabetes. These make patients who contract the coronavirus more vulnerable.
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In the early days of the coronavirus pandemic, researchers detected an unusual pattern among COVID-19 cases in China: more men were dying than women.

A study of more than 44,000 patients conducted by the Chinese Center for Disease Control and Prevention found that 2.8% of Chinese men diagnosed with the virus ultimately died as of February 11. For women, however, the fatality was 1.7%.

The trend, it later turned out, weren't exclusive to China. Italy, Germany, Iran, France, and South Korea have also reported a higher death toll among male patients, according to a recent analysis from CNN and academic research group Global Health 50/50.

The analysis found that among those five countries and China men were 50% more likely than women to die after being diagnosed with COVID-19.

More men than women have died Western Europe

The World Health Organization reported that as of March 20, men represented around 70% of coronavirus deaths in Western Europe. Men also represent around 70% of coronavirus deaths in Italy, according to data from the Italian National Health Service.

An analysis of more than 25,000 coronavirus cases from the Higher Health Institute of Rome found that male coronavirus patients in Italy had a fatality rate of 8%, compared to 5% for Italian women.

The same analysis found that men only represented a slight majority of Italy's coronavirus cases: around 58%.

"From Italy, we're seeing another concerning trend, that the mortality in males seem to be twice in every age group of females," Deborah Birx, the White House's coronavirus response coordinator, warned at a press briefing earlier this month.

The data seems to track with that of other countries as well.

In Spain,the Carlos III Health Institute found that men represented around 52% of the country's coronavirus cases , but 66% of coronavirus deaths. That amounts to double the number of coronavirus deaths among men than women (376 compared to 190).

Spain coronavirus PAU BARRENA/AFP via Getty Images

Men represent the minority of cases in South Korea

South Korean data is a bit more of an outlier: As of Thursday, men represented the minority of coronavirus patients in South Korea, around 40%. But they still represented a slight majority of coronavirus deaths: around 52%.

That means the fatality rate for men in South Korea is around 1.9% compared to 1.1% for women.

It's important to note, however, that South Korea has far fewer cases in total than Italy, Spain, or China, since the nation was able to slow the spread of the virus relatively quickly.

The nation has reported around 9,500 cases compared to more than 80,000 cases in Spain, 82,000 in China, and 97,000 in Italy. (South Korea's population is 51 million, while Spain's is 47 million, Italy's is around 60 million, and China's is 1.3 billion.)

US data is incomplete, but men represent the most deaths in New York City

The US Centers for Disease Control and Prevention has not yet released a breakdown of the gender of coronavirus patients, but some cities and states have provided their own data.

On Tuesday, New York City's health department reported that men accounted for 56% of the city's coronavirus cases and 61% of coronavirus deaths there. This offers a strong indication of how the virus affects people nationwide, since New York is the epicenter of the US outbreak.

New York David Dee Delgado/Getty Images

On Monday, Milwaukee, Wisconsin, also confirmed that the majority of its coronavirus cases there were middle-aged African American men .

"When we're talking about various health outcomes like infant mortality, childhood lead poisoning, you see very similar distributions," health commissioner Jeanette Kowalik told the Milwaukee Journal Sentinel .

Men's habits could play a role

One possible explanation for the higher death rates among men could be that they smoke cigarettes more than women do, on average. Smoking increases the risk of a range of respiratory problems. More than 50% of Chinese men smoke, while less than 3% of Chinese women smoke, according to the Chinese Center for Disease Control and Prevention.

In Italy, also, 7 million men smoke compared to 4.5 million women, according to the Italian National Health Institute.

The Italian National Health Institute said the chances that smokers need intensive care and mechanical ventilation are more than double the risk for nonsmokers.

italy coronavirus Claudio Furlan/LaPresse via AP

There is also some speculation that behavioral factors could explain some of the gender disparity surveys suggest US men are less likely to wash their hands and less likely to use soap . Hand-washing is one of the most important preventative steps to avoid contracting and spreading the disease.

Men may also have more comorbidities

Some researchers suspect that certain biological factors might make men more susceptible to severe cases of COVID-19. A study in mice done at the University of Iowa , for instance, found that genes on the X chromosome and hormones such as estrogen could make female mice less susceptible to SARS, another type of coronavirus. (The new coronavirus shares 79.5% of its genetic code with SARS.)

Research has also shown that people with preexisting health conditions like high blood pressure more commonly develop severe coronavirus symptoms. And in many countries, men have higher rates of these underlying health issues.

"The fatality rates are closely associated to age and comorbidities, and in Spain older men have a lot more of these," Germn Peces-Barba, vice president of the Spanish Pneumology and Thoracic Surgery Society, told the Spanish newspaper El Pas .

According to CNN , Italian men also have higher rates of high blood pressure than women. So do Chinese men , and they are also are more likely to have Type 2 diabetes than Chinese women.

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