INTRODUCTION
During the pneumonia epidemic that emerged in Wuhan, China in December 2020, pneumonia due to the newly defined severe acute respiratory syndrome coronavirus 2, known as SARS-CoV-2, was defined as coronavirus disease-2019 (COVID-19). Patients presented with both asymptomatic and flu-like symptoms and showed different clinical courses, from pneumonia to respiratory failure (1, 2). Thorax computed tomography (thorax CT) is very sensitive to identifying viral pneumonia. In all age groups, patients with COVID-19 pneumonia generally have bilateral, peripheral and multifocal involvement in lung radiology, and ground-glass densities, consolidation and vascular enlargements can be seen in thorax CT (3). COVID-19 generally affects entire populations, but older people with underlying diseases are more susceptible (4). COVID-19 can cause asymptomatic or mild upper respiratory tract symptoms in young persons, and diffuse lung involvement is observed in some cases. The majority of patients who develop moderate to severe disease are over 50 years old, although there has been a substantial minority of young people requiring hospitalisation and mechanical ventilation (5). However, how the disease will progress in each patient is still unknown. Therefore, we aimed to investigate the prognostic markers of the development of pneumonia and the clinical characteristics of patients under 65 years with COVID-19 infection confirmed by a positive reverse transcriptase polymerase chain reaction (RT-PCR) test.