Explained: Is lung fibrosis a lasting signature of Covid-19?

How common is lung fibrosis in Covid-19 patients?

It’s quite routine. While the vast majority of the almost 60 million people who have contracted the virus around the world have had only a mild or moderate infection, about 10% will develop severe Covid-19 pneumonia, and 5% will develop Acute Respiratory Distress Syndrome (ARDS). Given the overall numbers of those infected with SARS-CoV-2, this still works out to significant pulmonary involvement in several million individuals.

India has had more than 92 lakh cases and over 1.34 lakh deaths so far. “We are routinely seeing this dreadful fibrosis,” Dr Udwadia said. Even back in July, Dr Randeep Guleria, Director, AIIMS, and the country’s leading pulmonologist, had said post-Covid recovery clinics must extensively follow up on patients to see the impact of the virus on other organs as well. “We have seen a number of patients who have severe pneumonia, where lungs get totally scarred. Although they come out, some of them require oxygen at home after recovery. Three months down, CT scans have shown lungs are in bad shape,” Dr Guleria had told The Indian Express in an interview. 📣 Express Explained is now on Telegram

And how serious is the threat from lung fibrosis?

Some three decades ago, lung fibrosis was less common. It usually occurs in elderly people, where the lungs become stiff and the ability of oxygen to enter the blood circulation diminishes. If the Covid-19 virus causes lung fibrosis as a sequelae to the coronavirus disease pneumonia, large numbers of cases may potentially result from the pandemic, Dr Sundeep Salvi, chest physician and director of the Pulmo Care Research and Education Foundation, said.

The full fallout of the Covid-19 epidemic remains to be seen, but knowledge of closely related coronavirus outbreaks like Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) has led experts like Dr Udwadia to hypothesise that while the majority of patients will stabilise or improve over time, some will progress to advanced lung fibrosis or PC-ILD. The sheer scale of the pandemic suggests that physicians are likely to encounter potentially hundreds of thousands of individuals with PC-ILD, Dr Udwadia said.

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Which patients are at greatest risk of developing long-term pulmonary abnormalities?

It is too soon to determine that, according to the Lung India review (Udwadia et. al). Those with moderate or severe disease, with persisting symptoms or with radiological abnormalities, would require further investigation. An accurate biomarker that would predict which Covid-19 patients are likely to progress to fibrosis would be invaluable, the experts have said in the article.

Dr Udwadia cited the case of a 45-year-old non-smoker in intensive care with severe Covid-19 ARDS who progressed within 28 days to end stage fibrotic lung disease, despite receiving remdesivir, tocilizumab, dexamethasone, and even 500 mg pulses of methylprednisolone.

Nine months into the pandemic in India, steroids are now part of standard care in most severely ill hospitalised Covid-19 patients — however, the usual doses that most receive do not seem sufficient to prevent some of the patients from being left with residual lung shadows, Dr Udwadia said.

What role can anti-fibrotic drugs play in the prevention and treatment of post-Covid fibrosis?

That again, remains unclear at present. But there is a rationale for their potential usefulness.

Covid and Idiopathic Pulmonary Fibrosis (IPF) have common demographic factors — they affect males, the elderly and smokers more. Anti-fibrotic drugs are believed to be useful in patients with acute severity of interstitial lung disease (ILD), Dr Udwadia said.

Brig. (Dr) M S Barthwal, retired professor and Head of Department of Pulmonary Medicine at Pune’s Dr D Y Patil Medical College, Hospital and Research Centre, said there are very few studies on which anti-fibrotic drugs can lessen the progression of fibrosis. Apart from the drugs, there should be focus on supportive management as well — giving home oxygen therapy, chest physiotherapy (breathing exercises under supervision) and good nutrition, Dr Barthwal said.

According to Dr Udwadia, since it is patients with the most severe ARDS that are most likely to end up with fibrosis, this might be the group to consider for use of anti-fibrotic drugs. Such patients will generally require prolonged ventilation with high oxygen requirements, and perhaps anti-fibrotics along with steroids, he said.

To better understand the natural course of the disease, follow-up visits are recommended, either remotely or in person, up to a total duration of 36 months, based on the degree and extent of lung involvement.

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