Explained: How coronavirus enters lungs, affects breathing

Explained: How coronavirus enters lungs, affects breathing

Image of a COVID-19 patient’s lungs at a hospital in Belgium. (AP Photo)

In the picture still emerging on COVID-19, some trends have been noticeable as of now — many of those infected have recovered, while less than 80,000 have died out of the nearly 1.4 million cases so far. But when it has killed — usually the elderly and those with underlying conditions — the novel coronavirus (SARS-CoV2) has often done so by leading to pneumonia, the eventual cause of death. How does the virus affect the lungs?

Coronavirus: Outside lungs & inside

Once the virus enters the body, it can cause discomfort when it reaches the air passages on the outside of the lungs. These passages conduct air into and from the lungs. The virus injures the lining of the passageways, and the body responds with an inflammation, which in turn irritates the nerves in the lining. That is when an infected person coughs.

Infection can be more severe if the virus goes past the lining of the airways, and reaches the air sacs at the end of the air passages. Called alveoli, these sacs are responsible for the exchange of gas in the lungs. If they get infected, the sacs respond with inflammatory fluids, which fill the air sacs. That is what leads to pneumonia — when the lungs’ ability to transfer oxygen is impaired, and the infected person has difficulty breathing. When a person cannot inhale enough oxygen and exhale enough carbon dioxide, pneumonia can lead to death.

Also read | This 3D video shows how quickly coronavirus can attack a healthy person’s lungs

Who should worry?

The description above is of those who are the most severely affected. In most cases, the individual will recover after showing symptoms of varying severity, or none at all.

The least serious patients will show no symptoms after catching the virus. Some others will get an infection in the upper respiratory tract — at the lining of the lungs as described — and will develop a cough, may also have a fever, and will be potential carriers of the virus. The asymptomatic and mildly symptomatic groups are relatively small compared to those with somewhat more severe symptoms, resembling those we associate with a flu. In expert comments to The Guardian, Prof John Wilson, president-elect of the Royal Australasian College of Physicians and a respiratory physician, said those with flu-like symptoms are the largest group of patients.

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Then there are the extremely severe cases. These are the ones who will develop severe illness including pneumonia. So far, such extreme cases have been significantly fewer than those with flu-like symptoms,

Pneumonia as a result of COVID-19 is viral pneumonia, which means it cannot be treated with antibiotics. In severe cases, ventilator support may be needed to ensure sufficient oxygen circulation in the body.

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