Coronavirus symptoms: COVID-19 causes ‘irreversible’ lung damage

While 80 per cent of the population will only endure mild illness if infected with COVID-19, for one in six people the lung damage the virus causes can be “irreversible”.

For roughly 80 per cent of the population, becoming infected with coronavirus will result in a relatively mild illness that lasts about two weeks, according to the World Health Organisation (WHO).

But for every one in six people, the virus – which has infected almost two million people around the world and killed close to 120,000 – can become life-threatening, with 15 per cent of cases requiring oxygen and 5 per cent of cases in such a critical state they require ventilation.

Almost all serious consequences of the disease feature pneumonia, according to president-elect of the Royal Australasian College of Physicians and respiratory physician John Wilson.

When people get a large dose of COVID-19 it can overwhelm their immune system, which then overcompensates with inflammation that spirals out of control. This results in viral pneumonia, where air sacs (alveoli) in the lungs fill with fluid and it becomes difficult to breathe, Prof Wilson told The   Guardian Australia.

“The inflammation caused by the body’s immune response to the virus can cause the alveoli to pop, giving the lungs a honeycomb-type appearance or to harden so they are no longer able to do their job,” Dr Amir Khan, who works from England’s NHS, wrote in an article for Al Jazeera.

“When this happens, a condition similar to fibrosis or hardening of the lungs occurs.”

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A doctor shows the lungs of a COVID-19 patient on a computer screen at the MontLegia CHC hospital in Belgium. Picture: AP Photo/Francisco Seco

A scan of the lungs of a patient infected by COVID-19 at the Floreal clinic near Paris. Picture: Ludovic Marin/AFP

According to the WHO, severe acute respiratory syndrome (SARS), a coronavirus that behaves similarly to COVID-19, had a similar impact on the lungs of those with severe infection and led to permanent damage that affected their ability to breathe normally.

“For a small number of people who are severely affected by the disease, breathing normally may never be the same again, and getting short of breath on minimal exertion or requiring medication to help you breathe may become the norm,” Dr Khan explained.

Chief of thoracic surgery at the George Washington Hospital, Dr Keith Mortman, told CNN when the lungs encounter a viral infection, the organ will start to seal the virus off – with the damage to the lungs “rapid and widespread”.

“Unfortunately, once damaged to this degree, the lungs can take a long time to heal,” he said, adding “irreversible” damage can be caused.

Hong Kong Hospital Authority Infectious Disease Centre medical director Owen Tsang Tak-yin told media in March some patients who experienced severe cases of COVID-19 “might have around a drop of 20 to 30 per cent in lung function” after full recovery.

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The virus infection also damages the lining of the lung, so bacteria can invade more easily – which can then lead to bacterial pneumonia. And while bacterial pneumonia can be treated with antibiotics, it can also contribute to death.

The WHO has found the elderly or people with underlying health issues like high blood pressure, heart problems or diabetes to be more susceptible to developing a severe illness from COVID-19 – and chair of Lung Foundation Australia and respiratory physician Professor Christine Jenkins told The ï»¿Guardian Australia age was also a factor when it came to pneumonia.

“Age is the predictor of risk of death from pneumonia,” Prof Jenkins said.

“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.”