Lung damage could be permanent for some coronavirus patients, but new scans show significant healing after 12 weeks

• COVID-19 patients in Austria showed signs of lung damage six weeks after they left the hospital.
• But many patients saw their CT scans improve after 12 weeks, which could be a sign that their lungs will heal over time.
• However, once scarring occurs, the damage can't be undone.

First, the bad news: Six weeks after leaving the hospital, a majority of COVID-19 patients still showed signs of lung damage, according to a recent report.

But the research, which was presented at the European Respiratory Society International Congress earlier this month, also offered some hope: Some patients showed signs of improvement after 12 weeks.

For the study, which is still ongoing, researchers in Austria looked at 86 patients who'd previously been hospitalized with the coronavirus. They found that 88% showed white patches on their CT scans six weeks after they were discharged. These patches, known as ground glass opacities, indicate the presence of fluid and inflammation in the lungs.

But six weeks after that (12 weeks after discharge), only 56% of the patients had lung damage on their CT scans. Some patients also seemed to be breathing easier. Only 39% of patients said they had trouble breathing by the 12-week mark, compared to 47% at six weeks.

The research confirms that the virus can produce long-lasting physical damage, but it also suggests that patients' lungs might be capable of healing over time.

That's good news for the growing share of COVID-19 patients whose recovery processes have lasted well beyond their hospital visits. An Italian study in July found that 87% of patients who were hospitalized with COVID-19 still had symptoms — including difficulty breathing — two months after their illness began. And last month, a UK study that's still awaiting peer review found that 12% of COVID-19 patients had abnormal chest X-rays 12 weeks after they were admitted to the hospital.

Lung scans show improvement over time

Scientists worry that lung scarring — known clinically as pulmonary fibrosis — among coronavirus patients could be permanent and lead to a lifetime of breathing problems.

But the Austrian researchers found that fewer parts of the lung were damaged after six weeks relative to when the patients arrived at the hospital, and further improvement was seen after twelve weeks.

One 56-year-old male patient studied contracted COVID-19 in March and was admitted to the ICU with severe lung damage, shown in red in the scan below.

The man was discharged in late April. Six weeks later, his scans had drastically improved, as visible in the scan on the left below. After 12 weeks (the scan on the right), the majority of his lungs had started to heal.

"You're going to take one of three trajectories: either this will all reverse within the next three to six months, this is where you'll plateau, and for some patients, it may get gradually worse," Dr. Panagis Galiatsatos, a pulmonary physician at Johns Hopkins Bayview Medical Center who wasn't involved in the research, told Business Insider.

Right now, he said, predicting the odds of permanent lung damage among coronavirus patients is like flipping a coin.

"The long-term damage that we would see, like fibrosis, doesn't happen quickly," he said. "That can take up to a year before it develops. You can see early signs, of course, in a CAT scan, but even then it's hard to know if that's going to reverse or not."

Scarring is permanent, but it doesn't always lead to breathing problems

To see how a patient is recovering from the coronavirus, doctors also perform breathing tests to evaluate lung function, measuring how much air a patient can inhale or how much oxygen passes from the lungs to the blood.

Patients who have trouble breathing don't always have signs of damage on their CT scans. And patients with abnormal lung scans may not have trouble breathing.

"I have patients, believe it or not, coming in and their CAT scans still look horrible, but they're feeling great. They're like, 'No, I'm back to running a mile,'" Galiatsatos said. "That to me is part of the healing process."

Galiatsatos said he doesn't typically declare anything permanent until it has persisted for a year or more. But once lung tissue has been replaced with scar tissue, the physical damage can't be undone.

Still, even patients with scar tissue may eventually feel like their normal selves again.

"I definitely put a lot more stock in endurance," Galiatsatos said. "People with scarring can still live a happy life."

Ventilators may cause some damage

Galiatsatos said most of the lung damage among COVID-19 patients is likely caused by the virus, but other factors may contribute. As doctors learn more about how to treat severe cases, they've started to rethink the use of mechanical ventilators for all but the most severe cases.

A July study from New York University found that 22% of hospitalized COVID-19 patients were put on mechanical ventilators at the height of the pandemic in New York City. These patients had a higher rate of lung damage from the ventilators than patients who'd been intubated for other illnesses.

But Galiatsatos said ventilators shouldn't cause much damage if administered properly.

"Like any medical intervention, if not done well, it can pose a risk to the patient," he said. "If somebody goes in and turns up that ventilator to the highest pressure setting, you may cause permanent damage to the lungs over time."

What's more concerning, he said, is that patients on ventilators don't exercise their breathing muscles — particularly if they spend weeks to months in the hospital.

Compared to most ICU visits, hospital stays for COVID-19 patients are abnormally long, Galiatsatos said: One of his patients has been in the ICU since April.

Lung function can improve through rehab

Other recent research suggests that physical therapy can speed up the recovery process for COVID-19 patients with lung damage.

A coronavirus rehab program at the Dieulefit Santé clinic in France recently tracked the recovery of 17 patients who'd spent three weeks, on average, in the ICU. The patients who recovered faster spent less time bedridden, they found.

"The sooner rehabilitation started and the longer it lasted, the faster and better was the improvement in patients' walking and breathing capacities and muscle gain," Yara Al Chikhanie, a PhD student leading the research, said in a statement. "Patients who started rehabilitation in the week after coming off their ventilators progressed faster than those who were admitted after two weeks."

Galiatsatos also runs a rehabilitation clinic for coronavirus patients at Johns Hopkins.

"I always tell patients: There's no a medication to make your lung stronger. The only way to make them stronger is by using them," he said. "Every time you do some exercise and so forth, more blood flow gets to the lungs. More blood flow means more healing cells will come to heal the parts that are damaged."

In that regard, the recovery process for COVID-19 patients is akin to repairing a torn muscle or broken bone.

"I have a patient right now that came to the clinic [after they] lost 20% of their lung function," Galiatsatos said. "Right now, because of rehab, they feel as they felt prior to COVID."