When Annie Coissieux tried to stand up for the first time after weeks in the hospital battling Covid-19, she couldn’t get on her feet.
“My first day after I.C.U., I couldn’t leave the chair without the help of two nurses,” she recalled from her home in the Drôme region in southeast France. She felt breathless and exhausted after walking for just a few minutes. “Going to the bathroom was a real mission that required time and effort.”
Ms. Coissieux, 78, was sent to a nearby pulmonary rehabilitation clinic, Dieulefit Santé, where a physical therapist taught her breathing exercises to help restore her lungs and the muscles involved in breathing.
When she went home three weeks later, Ms. Coissieux could walk close to 1,000 feet, albeit with a walker. As she continued exercising at home, she grew stronger.
“Now I can walk 500 meters with no walker,” or about 1,600 feet, said the retired schoolteacher. “I can walk up the stairs at my cousin’s house.” And while she still feels fatigued in the afternoons, she cycles on her indoor bike and swims.
Lingering shortness of breath and diminished stamina have dogged many Covid patients whose lungs were viciously attacked by the coronavirus. Early in the pandemic, doctors worried that Covid might cause irreversible damage leading to lung fibrosis — progressive scarring in which lung tissue continues to die even after the infection is gone.
According to the World Health Organization, about 80 percent of patients have mild to moderate symptoms, 15 percent develop a severe form of the disease and roughly five percent like Ms. Coissieux escalate to critical.
While global or nationwide statistics on post-Covid lung recovery are not yet available, hospitals and clinics are assessing their cases.
About 20 percent of hospitalized Covid patients wound up in intensive care units, where many needed ventilators, according to Dr. Gabriel C. Lockhart, a pulmonologist at National Jewish Health, a respiratory hospital in Denver, who also volunteered at Mount Sinai Hospital in New York City. “Of the ones who get intubated at least two-thirds will survive but will require some physical therapy,” he said.
It’s not known yet how many people will rebound to their pre-Covid status, because so many are still recovering, said Dr. Jafar J. Abunasser, a pulmonologist at Cleveland Clinic. He added that one study of SARS, another coronavirus, published in the journal Chest found that about 59 percent of survivors had no lung impairment after one year, while one-third still had some lung abnormalities, which he described as “mild.”
During this year’s pandemic, few patients suffered such severe lung damage that they required lung transplants, still a rarity worldwide. But that number may climb as some patients’ lungs will not improve sufficiently, Dr. Sadia Shah, a pulmonologist at the Mayo Clinic in Jacksonville, Fla., said.
At a recent European Respiratory Society meeting, doctors presented early results of a few small studies that offered a glimmer of hope, indicating that in at least some cases, patients’ lungs show signs of recovery especially with intensive aftercare and exercise.
Yara Al Chikhanie, a doctoral student in lung physiopathology at the Dieulefit Santé, cited the clinic’s rehabilitation study of 19 patients at the session.
For patients who were bedridden or intubated in intensive care units for weeks, the ability to breathe on their own was impaired. Their muscles, including the diaphragm — the main breathing muscle that pushes the abdominal organs down so that the lungs can expand — had weakened.
“They spent months in bed and lost their muscle and respiratory capacity,” Ms. Al Chikhanie explained.
“It seems that most of these more severe patients recover from severe lung injury,” said Dr. Frederic Hérengt, who oversaw the study at Dieulefit Santé.
Longer range studies still have to be conducted to assess the potential for permanent effects.
Doctors at the University Clinic of Internal Medicine in Innsbruck, Austria observed similar improvements in their 86 patients, who were also in the hard-hit category and endured long hospital and I.C.U. stays.
Even after rehabilitation, many were still coughing and short of breath as they went home, equipped with exercise instructions and breathing devices — small, inexpensive plastic tubes that require one to breathe in and out with force.
But as they came back for checkups weeks later, their CT scans showed improvement, doctors said. Fluids were clearing from their lungs, and the white-glass lesions often seen in Covid pneumonia were lessening, sometimes disappearing entirely and sometimes noticeable only as thin white bands.
“There are some signs of reversible damage,” said Dr. Thomas Sonnweber, who conducted the study with his colleagues Dr. Judith Löffler-Ragg and Dr. Ivan Tancevski. At the time the patients were discharged from the hospital, 88 percent had lung damage, but 12 weeks later, only 56 percent did.
Their symptoms also improved. They coughed less, breathed and walked more easily, in some cases with markedly improved endurance.
“We have seen patients who went on wheelchairs to rehabilitation but they start walking again,” Dr. Löffler-Ragg said. She cited one particular case of an elderly man who needed oxygen before rehabilitation, but now walks up the stairs to his fourth-floor apartment with only mild shortness of breath. “Despite his 78 years, despite Covid pneumonia, he can manage this,” she said.
Neither study has been peer-reviewed or published in a scientific journal. But the patients’ improvement was encouraging to others who have been treating Covid patients.
Our lungs have good inner healing mechanisms, said Dr. Panagis Galiatsatos, an assistant professor who specializes in pulmonary and critical care at Johns Hopkins Bayview Medical Center in Baltimore.
The infection leaves behind a mess of dead cells, damaged tissues and fluids, caused by the coronavirus and the overzealous response of the immune system that often occurs in Covid patients. But once the infection is gone, the lungs begin to rebuild themselves, using specialized cells devoted entirely to healing.
“They create new cells to replace the diseased ones,” Dr. Galiatsatos explained. “There are also other cells that try to not only create new cells but promote the architecture of the lungs — not just recreating it, but recreating it to look exactly as it did before.”
When that’s not possible, scars will form and some may become permanent, but that serves a purpose too. The lungs know that the scarred spot can’t perform oxygen exchange, so they won’t send blood there. “It’s called a shunt,” Dr. Galiatsatos said, adding that the lungs will adapt. “They’re going to send the blood to the more healthy parts.” Breathing and physical exercises can aid this recovery.
Even some patients originally deemed as candidates for a lung transplant managed to recuperate and go home without needing one, said Dr. Tiago Noguchi Machuca, a lung transplant surgeon at the University of Florida.
He had treated patients on ventilators and ECMO machines — devices that infuse oxygen into the blood stream and remove carbon dioxide — who managed to get them off life support and breathing on their own. His team keeps such patients on ECMO machines, but tries to take them off ventilators to restore their breathing capacities, he said.
One patient was about to go home soon. “We had brought him here really thinking he was going to need a transplant,” Dr. Machuca said. “And he recovered.”
Doctors don’t yet know how long it will take patients to regain their pre-Covid strength and endurance. In the case of acute respiratory distress syndrome or ARDS, which has been caused by other viruses and has similarities to Covid-19, full recovery can take over a year, but there are no such statistics for Covid yet.
However, the earlier patients start their rehabilitation, the faster they begin to bounce back, which may be another reason for doctors to take them off ventilators sooner, Ms. Al Chikhanie said. That may be possible, especially as scientists understand how to manage the acute infection phase better.
Doctors at Mount Sinai found that Covid doesn’t break down the lung’s blood vessels but rather dilates them, which makes the blood flow too fast for the oxygen to be absorbed, causing hypoxemia or low levels of oxygen in the blood. Dr. Hooman Poor, a pulmonologist and co-author of the Mt. Sinai paper, said that more research was needed to identify efficient ways to reduce Covid-induced hypoxemia in patients.
Some people who spent a long time on life support can recover, though they will need a great deal of help and perseverance. “Stay active, move and walk around the house, go up and down stairs,” Ms. Al Chikhanie said.
But research is still very nascent about finding the best therapies to help Covid survivors restore their strength and lung capacity. “We really need a couple of years of data, it’s far too early for us to have the data about this pandemic,” Dr. Abunasser of the Cleveland Clinic said.
Annie Coissieux interviewed with Yara Al Chikhanie’s translation from French. Denise Grady contributed reporting.