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October 21, 2020

Is Covid-19 lung damage reversible? Here's what the evidence says.

Daily Briefing

    Many Covid-19 patients are affected by severe lung damage, and doctors have feared that damage may be irreversible. But preliminary research now suggests that may not be the case, Lina Zeldovich reports for the New York Times.

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    Currently, there's no global or nationwide data detailing lung recovery in Covid-19 patients. However, some hospitals and providers are releasing small samples of data showing how their Covid-19 patients have recovered, Zeldovich reports.

    For instance, at a recent meeting of the European Respiratory Society, Yara Al Chikhanie, a doctoral student in lung physiopathology at the Dieulefit Santé, presented a rehabilitation study of 19 patients at the clinic. The study showed that, among Covid-19 patients who were bedridden or intubated in the ICU for weeks, there was a noted decrease in the patients' ability to breathe, as their muscles (including the diaphragm) had weakened.

    "They spent months in bed and lost their muscle and respiratory capacity," Al Chikhanie said.

    But according to Frederic Hérengt, who oversaw the study, "[i]t seems that most of these more severe patients recover from severe lung injury." In fact, "[a]ll patients had a significant recovery and returned to normal in the following parameters: lung volumes and capacities, leg and handgrip strengths, respiratory pressures, balance, anxiety, and depression," the researchers wrote in the study.

    Separately, doctors at the University Clinic of Internal Medicine in Austria in data published in June reported that they saw improvements in 86 Covid-19 patients who had been in the hospital and/or ICU for a long time, Zeldovich reports. After rehabilitation, many of the patients still experienced shortness of breath and coughing when they went home. According to the doctors, at the time of discharge, 88% of the patients had lung damage.

    However, when the patients came back for checkups weeks later, their CT scans showed improvement, with fluid clearing from their lungs and the white-glass lesions that often appear in patients with Covid-19-related pneumonia lessening or disappearing entirely, according to the doctors. At the 12-week mark, the percentage of patients who had lung damage dropped to 56%, the doctors found. The patients' symptoms also improved, with patients experiencing less coughing and finding it easier to breath and walk, the doctors said.

    Overall, Thomas Sonnweber, who conducted the study alongside Judith Löffler-Ragg and Ivan Tancevski, said, "There are some signs of reversible damage."

    Löffler-Ragg added, "We have seen patients who went on wheelchairs to rehabilitation but they start walking again." She noted that one elderly patient had required oxygen before rehabilitation, but the patient now can walk the stairs to his fourth-floor apartment with just mild shortness of breath. "Despite his 78 years, despite Covid pneumonia, he can manage this," Löffler-Ragg said.

    But neither of those studies have been peer-reviewed or published at this time, Zeldovich reports, and the researchers have said more study is needed to assess Covid-19 recovery.

    What we know—and don't know—about lung recovery after Covid-19

    According to Panagis Galiatsatos, an assistant professor specializing in pulmonary and critical care at Johns Hopkins Bayview Medical Center, Covid-19 leaves a lot of dead cells, damaged tissues, and fluids behind as a result of the way the novel coronavirus progresses and the intense immune system response that often occurs in response to the virus. However, once that infection is gone, the lungs start to rebuild and create "new cells to replace the diseased one" and "promote the architecture of the lungs," Galiatsatos said.

    If that can't happen, scars will form—some of which will be permanent. However, the lungs will know that the scarred portion, called a "shunt," can't perform oxygen exchange, so blood won't be sent there and will instead be sent "to the more healthy parts," Galiatsatos said.

    But there's still plenty doctors don't know about how the lungs of Covid-19 patients recover, Zeldovich reports.

    For example, it's not known just how many patients will return to their pre-Covid health, Jafar Abunasser, a pulmonologist at the Cleveland Clinic, said.

    Abunasser noted that research on Covid-19 lung recovery is still in early stages, and therefore offers only a limited picture of what recovery from the disease may look like. "We really need a couple of years of data, it's far too early for us to have the data about this pandemic," Abunasser said (Zeldovich, New York Times, 10/19; Al Chikhanie et al., New York Times document, accessed 10/19).

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