A blood test that can identify Covid-19 patients at high risk of developing pneumonia and severe lung complications at an early stage could soon be available, so that they can be treated accordingly.
The discovery has raised hopes that existing treatments, such as the Cholesterol-lowering statin Simvastatin and the gout treatment Colchicine, could be an effective way to treat or prevent Covid-19 pneumonia.
Researchers found that patients with high levels of CR3, a protein that activates the immune system, are at much greater risk of developing pneumonia, which is caused by an overactive immune response. Existing anti-inflammatory treatments could tackle the problem because they are designed to curb CR3 activity.
“We saw striking and unexpected differences in the cells of the immune system between Covid-19 patients. Levels of CR3 were increased from Covid-19 patients experiencing respiratory failure, but not in those with Covid-19 who remained well,” said lead researcher Rajeev Gupta, of University College London.
Plan treatment accordingly
“Our findings suggest tracking CR3 levels in patients with COVID-19 could help us assess disease severity. By identifying which infected individuals are at risk of severe illness at an early stage we could plan treatment accordingly,” he added.
“Targeting CR3 with drugs such as Colchicine or Simvastatin could be an effective way to prevent or treat COVID-19 pneumonia. And in the absence of an effective vaccine, preventing lung failure in Covid-19 patients would be an ideal intervention,” he said.
The study also found that the number of so-called Natural Killer (NK) cells – a key part of the immune system contained in white blood cells – was twice as high in Covid patients with mild symptoms as in those with severe symptoms, potentially providing another ‘biomarker’ of risk.
Covid-19 affects the body in different ways. Most infected people will experience mild to moderate symptoms, while others will progress to severe or critical disease, including pneumonia and acute respiratory failure.
Circulating monocytes
The researchers studied a type of white blood cell of the immune system, known as circulating monocytes, from a group of adult patients with Covid-19 and compared those with mild symptoms with those who had developed pneumonia.
They found that levels of the CR3 protein were higher in Covid-19 patients who had developed pneumonia compared with those who did not.
The study is published in the International Journal of Infectious Diseases.
Experts in the field not involved in the study said its results were promising, although they cautioned that more research was needed.
They pointed out that, at just 29 patients, the study was based on quite a small sample size – while the samples were not taken at the same stage of the disease for all participants, making it harder to carry out direct comparisons.