Is THIS Why Most Coronavirus Deaths Have Been In Chinese Men?

It is important not to panic about Coronavirus.  Panic makes everything worse.

But it's also vital for scientists to determine why some people are dying from the virus and others don't even know they're sick. And it is prudent to take some basic precautions on an individual basis.

After all, a new study from Los Alamos National Laboratory scientists shows that - before China instituted quarantines - every person with Coronavirus infected between 4.7 to 6.6 new people. This is called R0 (pronounced "R Zero" or "R Naught").  

The quarantine has lowered the R0 rate to between. 2.3 and 3. But this is still extremely infectious:

The coroneavirus epidemic could spread to about two-thirds of the world’s population if it cannot be controlled, according to Hong Kong’s leading public health epidemiologist. 

(And several experts have said that it is too late to stop its spread).

The latest scientific study out of China shows that the approximately 3% of the people who get Coronavirus die from it (i.e. the "mortality rate").

Most of the deaths are in people over 60 years old.

But that is not the only determinant.  For example, the mortality rate is apparently higher among men than woman.   And see this.  Indeed, more men than women also die of related diseases such as Sars and Mers

And even though the hospitals in Wuhan - where the virus started - are overwhelmed and so unable to provide intensive levels of care, it is still a bit surprising that virtually every single death from Coronavirus has been in China.

One Chinese study wondered whether Asian people are more susceptible genetically to Coronavirus and SARS:

We also noticed that the only Asian donor (male) has a much higher ACE2-expressing cell ratio than white and African American donors (2.50% vs. 0.47% of all cells). This might explain the observation that the new Coronavirus pandemic and previous SARS-Cov pandemic are concentrated in the Asian area.

The study has no statistical significance, given that the sample size included only a handful of people with a single Asian victim, and such a small sample size is meaningless.

But the reference to ACE2 may be on the right track. Specifically, most scientists agree that both the Wuhan Coronavirus and the SARS virus which hit China in 2002-2003 attack the human body through the ACE2 receptor (short for "Angiotensin-converting enzyme-2", which is an enzyme which plays a role in constriction of the lungs).

Here's where it gets interesting ...

A professor at the University of South Carolina found that smokers have significantly higher levels of ACE2 than non-smokers ... but that no difference was found based on age, gender or racial group: 

In this study, we analyzed four large-scale datasets of normal lung tissue to investigate the disparities related to race, age, gender and smoking status in ACE2 gene expression. No significant disparities in ACE2 gene expression were found between racial groups (Asian vs Caucasian), age groups (>60 vs <60) or gender groups (male vs female). However, we observed significantly higher ACE2 gene expression in smoker samples compared to nonsmoker samples. This indicates the smokers may be more susceptible to 2019-nCov and thus smoking history should be considered in identifying susceptible population and standardizing treatment regimen.

Could this could help to explain why Chinese men are more susceptible to Coronavirus than other people?

Actually, it might...

The Chinese smoke a lot.  BBC reported in 2015:

China is the world's biggest consumer of cigarettes - one in three cigarettes smoked globally is in China - as well as the world's biggest tobacco producer.

More than 300 million people - about a quarter of the population - smoke, with the average smoker consuming 22 cigarettes a day.

And it turns out that Chinese men smoke a lot more than Chinese women.  For example, Gallup reported in 2005:

Smoking in China is overwhelmingly a male habit. At least two-thirds of all Chinese men (68%) smoke at least occasionally, and roughly half (49%) are regular smokers. In contrast, only 6% of women smoke regularly (3%) or occasionally (3%).

Wikipedia writes:

China ... accounted for 51.4% of the world's male smokers in 2015.

BBC notes:

A new study has warned that a third of all men currently under the age of 20 in China will eventually die prematurely [from lung cancer and other diseases other than Coronavirus] if they do not give up smoking.

And a shockingly high percentage of Chinese male doctors smoke as well:

A 2004 study conducted among 3,500 Chinese physicians found that 23% were regular smokers. There was a significant gender difference, with 41% of male physicians reporting to be smokers but only 1% of female physicians. More than one third of current smokers had smoked in front of their patients and nearly all had smoked during their work shift.

***

The smoking rates from these independent studies are lower than those reported by China's state-run newspaper. An article published in 2009 interviewed a source who claimed that 60% of Chinese male doctors were smokers, a percentage higher than any other country's doctors in the world.

So - in addition to other factors such as the overwhelmed medical system in Wuhan, and the attempt of the national and local governments to wish the problem away for the first couple of weeks - the high smoking rates (and increasing ACE2 levels) might be one of the reasons that most deaths from Coronavirus have been among Chinese men.

In any event, smoking can obviously weaken the lungs ... making smokers less able to fight off the effects of Coronavirus. As the San Jose Mercury News notes:

The respiratory tract – from the nose and tonsil crypts all the way down to the lungs — is an excellent portal of entry for a virus.

The resulting lung inflammation and fluid buildup can lead to breathing distress. It also sets the stage for a secondary bacterial pneumonia.

And if the lungs are already damaged from smoking, age or other infections, then they’re much more susceptible to a harmful pathogen.When combined with chronic lung disease, the two problems cause more rapid decline in lung function and are more likely to cause rapid, permanent injury.

As the Financial Times points out:

Possible reasons for the disparities [between mortality rates in men and women] include smoking, changing hospital care and gender-related immune response. 

Postscript: Obviously, further study is needed to test whether or not the smoking-ACE2 hypothesis is accurate.  This is even more true because the Coronavirus has spread so quickly that credible scientists are rushing to publish their preliminary findings ... even before going through the standard peer-review process.    Specifically, they are trying to fight the effects of the virus by sharing their preliminary findings as quickly as possible, and they will go through the peer review process as soon as they can.