CSF2 and susceptibility to pneumonia measurement: In the group of GFs evaluated in this study, basic-FGF and GM-CSF were the most useful markers for diagnosing COVID-19 and for differentiating between asymptomatic/mildly symptomatic patients (stage 1) and patients with pneumonia without respiratory failure (stage 2), which indicates that these parameters can be useful biomarkers for assessing disease severity.