UVA Health researchers have discovered a potential way to identify which patients with severe COVID-19 are likely to recover well and which are likely to suffer long-haul lung problems, a finding that could better personalize treatments for individual patients.
The new research, published in Frontiers in Immunology, also eases concern that severe COVID-19 could trigger persistent and ongoing lung scarring akin to idiopathic pulmonary fibrosis (IPF), in which continuing lung damage eventually proves fatal.
“We are excited to find that people with long-haul COVID have an immune system that is totally different from people who have lung scarring that doesn’t stop,” said researcher Catherine A. Bonham, MD, a pulmonary and critical care expert and scientific director of UVA Health’s Interstitial Lung Disease Program. “This offers hope that even patients with the worst COVID do not have progressive scarring of the lung that leads to death.”
Prior research has found that up to 30% of patients hospitalized with severe COVID-19 continue to suffer persistent symptoms months after recovering from the virus. Many of these patients develop lung scarring either early on in their hospitalization or within six months of their initial illness.
Dr. Bonham and her collaborators wanted to better understand why this scarring occurs, determine if it is similar to progressive pulmonary fibrosis and see if there is a way to predict patients at risk.
Researchers followed 16 UVA Health patients who survived severe COVID-19, including 14 who were hospitalized and placed on a ventilator during treatment. All had trouble breathing and suffered fatigue and abnormal lung function at their first outpatient checkup.
After six months, researchers found that the patients could be divided into two groups. One group’s lung health improved, prompting the researchers to label them “early resolvers.” The other group, dubbed “late resolvers,” continued to suffer lung problems and pulmonary fibrosis.
The team examined blood samples taken before the recovery paths diverged and found that late resolvers had significantly fewer immune cells known as monocytes (white blood cells that play a critical role in fending off disease) circulating in their blood. The cells were abnormally depleted in patients who continued to suffer lung problems compared both to those who recovered and healthy control subjects.
The decrease in monocytes also correlated with the severity of the patients’ ongoing symptoms. The discovery suggests that doctors may be able to use a simple blood test to identify patients likely to suffer long-haul COVID-19 and to improve their care.
“About half of the patients we examined still had lingering, bothersome symptoms and abnormal tests after six months,” Dr. Bonham said. “We were able to detect differences in their blood from the first visit, with fewer blood monocytes mapping to lower lung function.”
The researchers also wanted to determine if severe COVID-19 could cause progressive lung scarring like IPF. They found the two conditions had very different effects on immune cells, suggesting that even though symptoms were similar, the underlying causes were very different. This held true in patients with the most persistent long-haul symptoms.
“Idiopathic pulmonary fibrosis is progressive and kills patients within three to five years,” Dr. Bonham said. “It was a relief to see that all our COVID patients, even those with long-haul symptoms, were not similar.”
Because of the small number of participants in UVA’s study, and because they were mostly male (for easier comparison with IPF, which is more common in men), the researchers say larger studies with other medical centers are needed to bear out the findings. Still, they are hopeful that their new discovery will provide doctors a useful tool to identify COVID-19 patients at risk for ongoing lung problems and to help guide them to recovery.
“We are only beginning to understand the biology of how the immune system impacts pulmonary fibrosis,” said Dr. Bonham.
