Coronavirus: what happens to people’s lungs if they get Covid-19?

What became known as Covid-19, or the coronavirus, started in late 2019 as a cluster of pneumonia cases with an unknown cause. 

The cause of the pneumonia was found to be a new virus -severe acute respiratory syndrome coronavirus 2, or Sars-CoV-2. The illness caused by the virus is Covid-19.

Now declared as a pandemic by the World Health Organisation (WHO), the majority of people who contract Covid-19 suffer only mild, cold-like symptoms.

WHO says about 80% of people with Covid-19 recover without needing any specialist treatment. Only about one person in six becomes seriously ill “and develops difficulty breathing”.

So how can Covid-19 develop into a more serious illness featuring pneumonia, and what does that do to our lungs and the rest of our body?

How is the virus affecting people?

Prof John Wilson, president-elect of the Royal Australasian College of Physicians and a respiratory physician.

Says almost all serious consequences of Covid-19 feature pneumonia.

Wilson says people who catch Covid-19 can be placed into four broad categories.

1.The least serious are those people who are “sub-clinical” and who have the virus but have no symptoms.

2. Next are those who get an infection in the upper respiratory tract, which, Wilson says, “means a person has a fever and a cough and maybe milder symptoms like headache or conjunctivitis”.

He says: “Those people with minor symptoms are still able to transmit the virus but may not be aware of it.”

3.The largest group of those who would be positive for Covid-19, and the people most likely to present to hospitals and surgeries, are those who develop the same flu-like symptoms that would usually keep them off work.

4. A fourth group, Wilson says, will develop severe illness that features pneumonia.

How does the pneumonia develop?

When people with Covid-19 develop a cough and fever, Wilson says this is a result of the infection reaching the respiratory tree – the air passages that conduct air between the lungs and the outside.

He says: “The lining of the respiratory tree becomes injured, causing inflammation. This in turn irritates the nerves in the lining of the airway. Just a speck of dust can stimulate a cough.

How can the pneumonia be treated?

Prof Christine Jenkins, chair of Lung Foundation Australia and a leading respiratory physician, Says “Unfortunately, so far we don’t have anything that can stop people getting Covid-19 pneumonia

Is Covid-19 pneumonia different?

Covid-19 pneumonia is different from the most common cases that people are admitted to hospitals for. “Most types of pneumonia that we know of and that we admit people to hospital for are bacterial and they respond to an antibiotic.

“Age is the major predictor of risk of death from pneumonia. Pneumonia is always serious for an older person and in fact it used to be one of the main causes of death in the elderly. Now we have very good treatments for pneumonia.

“It’s important to remember that no matter how healthy and active you are, your risk for getting pneumonia increases with age. This is because our immune system naturally weakens with age, making it harder for our bodies to fight off infections and diseases.”