What is already known about this topic?
Coronaviruses are among the main pathogens that mainly target the human respiratory system. Severe disease characterized by interstitial pneumonia develops in 10-20% of patients. Periostin has recently been shown to be an indicator of disease progression in idiopathic pulmonary fibrosis and asthma. In this study, we aimed to investigate whether periostin could be a useful new biomarker in the follow-up and severity assessment of the disease in patients with COVID-19 pneumonia.