COVID-19 has become a pandemic in many countries around the world, causing many deaths. Even if some people are infected, they may have no symptoms or only have mild symptoms, while others may progress to developing severe pneumonia. For people who are likely to become seriously ill, treatment should be started promptly after infection, but it has been difficult to predict at the early stages of infection whether or not the illness will become severe.

　In this study, we focused on metabolites in the blood (serum) in search of biomarkers to determine whether COVID-19 infection can become severe in the early stages. Since blood tests are very commonly used in clinical settings, and only a small amount of serum is required to measure metabolites, we attempted to search for biomarkers using serum.

　Sera from 5 patients in the early stages of infection (within 83 days of onset of symptoms) were analyzed using a mass spectrometer. As a result, they discovered that the amount of amino acid decomposition products differs in the early stages of infection between people with mild symptoms and those who later develop severe symptoms. Furthermore, as a result of visualizing the structures and metabolites in mouse lungs, it was found that airway and vascular tissue cells proliferate abnormally in the early stages of infection in the mouse lungs, which later become severe.

　From the present results, it was concluded that amino acid catabolites at the early stage of infection are an effective factor in predicting later severity. It is hoped that this will allow blood tests to predict whether a person is at risk of becoming seriously ill when they visit a hospital in the early stages of infection, within five days after symptoms appear.

Paper information:[Nature Communications] Amino acid catabolite markers for early prognosis of pneumonia in patients with COVID-19