CXCL9 and pneumonia: In the present study, IP-10 and MIG levels were higher in stage 2 patients (pneumonia without respiratory failure) than in stage 1 (asymptomatic/mildly symptomatic) patients, and other authors also reported high concentrations of these chemokines in patients with moderate and severe COVID-19, which suggests that these chemokines can be useful biomarkers for monitoring the progression of the SARS-CoV-2 infection.