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How does COVID-19 cause death? Here’s what happens in the lungs

This is what can happen to your lungs when you have coronavirus
The coronavirus pandemic continues to spread across Canada, infecting people young and old — and, in severe cases, it can leave a lasting mark on a patient's lungs.

EDITOR’S NOTE: This story contains sensitive information that can be disturbing to some readers.

More than 100,000 people worldwide have died as a result of the novel coronavirus. 

The majority of these deaths have occurred in Italy, France, Spain and the United States, according to Johns Hopkins University, which maintains a real-time worldwide case count.

One of the hardest-hit zones includes New York City, which now has the most confirmed cases than any other country and a death toll of more than 7,000 people. 

READ MORE: Coronavirus deaths top 100,000 worldwide

In Canada, more than 650 people have died as of April 12 and overall death projections for the country are between 11,000 and 22,000, according to the Public Health Agency of Canada earlier this week. The majority of Canadian victims are elderly residents in long-term care homes. 

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How does COVID-19 cause death?

While close to 370,000 worldwide have been able to recover from COVID-19, experts like Zahid Butt, an assistant professor at the University of Waterloo in Ontario, says survival depends on a patient’s lungs. 

“The coronavirus is a respiratory virus [that] invades the respiratory system. Coronavirus can infect both the upper and lower respiratory tract,” he said in an email to Global News.

Butt, who specializes in infectious disease epidemiology, says a COVID-19 infection starts from the nose and then proceeds to the lungs.

In most cases, the virus stays in the upper tract that includes everything above the windpipe, Butt said. In those cases, symptoms can include a fever, cough or a sore throat.

For some people, if the virus isn’t considered severe, it hasn’t entered the lungs.

Coronavirus outbreak: Pregnant woman with COVID-19 sits up for first time in days, struggles to breathe
Coronavirus outbreak: Pregnant woman with COVID-19 sits up for first time in days, struggles to breathe

Butt says if the virus migrates to the lower tract, that’s when symptoms like shortness of breath can occur.

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“Once the virus reaches the lungs, it causes inflammation which results in fluid accumulating in the lung and difficulty breathing,” he said. “This fluid fills the lung’s air sacs… [then] blood oxygen levels fall below normal, a condition known as pneumonia.”

The air sacs are responsible for gas exchange, which is the process of breathing in oxygen and removing carbon dioxide.

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The cell disruption that COVID-19 causes in the lungs is the main reason this illness causes a severe respiratory pathology, which is the behaviour and characteristics of the disease, said Narveen Jandu, an assistant professor at the University of Waterloo that specializes in microbiology and infectious diseases. 

READ MORE: This is what can happen to your lungs when you have coronavirus

“[Gas exchange] is an important and vital function for life. And that’s the exact function where the virus is disrupting during infection,” she said. 
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When the virus enters the air sacs, it interacts with a specific type of cell that lines the sacs called the alveolar cells — specifically called type II cells, she added.

The spike-like appearance of the novel coronavirus is how the illness is able to interact with a molecule on the type II alveolar cells, and then invade those cells, she said. 

“Once it gets inside these cells it’s going to start to replicate and multiply and divide and create copies of itself… and then because it infected that one cell of ours, that one cell of ours essentially gets destroyed and bursts open,” she said. 

When that cell bursts, it releases hundreds of new virus particles that can go on to infect more and more cells, Jandu said.

Why do some cases of the virus result in fatal outcomes?

Once the virus has started to destroy human cells that line the air sacs, how the immune system responds can contribute to the difference between a person being able to recover, and a possible fatal outcome, she explained. 

“Some people have a stronger immune system, and some people, not so strong,” she said. It’s been established that the elderly, and those with pre-existing conditions or those that have a compromised immune system will have a more difficult time fighting off the coronavirus, she said. 

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A person’s immune system will respond to the virus by causing fever and inflammation, which can cause fluid to leak into the lungs, further impeding breathing, she said. As breathing becomes more and more difficult, that’s the point where a person would need a ventilator to breathe, she added.

An overactive immune system that responds in an extreme way to the virus can cause “massive damage” in the body, whereas one that’s too weak can’t fight it off either, she explained.

READ MORE: Bedridden for days, young Canadians with COVID-19 say illness is ‘no joke’

Access to health care, racism a factor in surviving the coronavirus

It’s also important to note that inequities in health-care systems is a major factor in who survives a coronavirus infection, beyond immune response, said Suzanne Sicchia, an associate professor at the Interdisciplinary Centre for Health and Society at the University of Toronto Scarborough.

In the U.S., the virus is killing Black Americans at a much higher rate and 42 per cent of the nation’s 13,000 deaths so far are Black people, according to an analysis by the Associated Press.

Systemic racism and lack of access to health care have made Black Americans more vulnerable to the virus, according to the AP. In Canada, race-based statistics are not kept although there is also a consistent history of poorer health outcomes for Black and Indigenous Canadians due to the same factors. 

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“The burden of disease, sickness, and suffering is not evenly distributed in the population. This is so very important for us to truly acknowledge and work to make right,” said Sicchia in an email to Global News.

“The pandemic is showing us the importance of the social, political and economic determinants of health that produce these inequities. It’s up to us to decide to care enough to change these conditions, and in so doing move towards a more healthy and just society,” she said.

What we don’t know yet about COVID-19

Beyond understanding the immune system and our health-care systems, there are many aspects of the virus that are currently unknown to medical professionals, said Jandu.

“There could be something about the way it’s causing infection, something that… we just don’t know yet. Or it could be the fact that it’s something new and it’s spreading so quickly among the population,” she said.

READ MORE: Virus science — a look at coronavirus research around the globe

New research from a Chinese group of scientists has suggested there could be two strains of the virus, with one causing more severe outcomes. But new reports like this one haven’t had the opportunity to be reviewed extensively by the academic community, said Jandu.

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“We can’t draw conclusions from this work yet. There are a lot of reports coming out, and everything is just fresh off the press,” she said. There needs to be more time to peer review and critique the data before they can be taken with certainty, she explained. 

However, at the same time reports need to be released quickly so information can be shared about the virus, she said. More will be known as it continues to be studied.

This is something that is perplexing the scientific and biomedical community because it is such a new virus. We’re learning more and more about it every day…and we’re trying our best in real-time to understand how it’s causing infection and how is it’s causing pathology,” she said.

Questions about COVID-19? Here are some things you need to know:

Health officials caution against all international travel. Returning travellers are legally obligated to self-isolate for 14 days, beginning March 26, in case they develop symptoms and to prevent spreading the virus to others. Some provinces and territories have also implemented additional recommendations or enforcement measures to ensure those returning to the area self-isolate.

Symptoms can include fever, cough and difficulty breathing — very similar to a cold or flu. Some people can develop a more severe illness. People most at risk of this include older adults and people with severe chronic medical conditions like heart, lung or kidney disease. If you develop symptoms, contact public health authorities.

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To prevent the virus from spreading, experts recommend frequent handwashing and coughing into your sleeve. They also recommend minimizing contact with others, staying home as much as possible and maintaining a distance of two metres from other people if you go out.

For full COVID-19 coverage from Global News, click here.