Methods
Study population and data collection
This retrospective cross-sectional study was conducted in subjects who were diagnosed with COVID-19 pneumonia based on positive SARS-CoV-2 polymerase chain reaction result in combined nasal-throat swab sample and pulmonary infiltrates in computed chest tomography in a state hospital in Istanbul, Turkey between 11 March and 10 June, 2020. Study population was grouped according to severity of COVID-19 pneumonia according to Turkish Ministry of Health COVID-19 guide; 1) subjects with severe clinical condition with tachypnea (≥30 / minute), oxygen saturation below 90% breathing room air together with bilateral diffuse pulmonary infiltrates and hospitalized, 2) subjects with mild clinical condition followed up on an outpatient basis.5
Sociodemographic characteristics, body-mass index, smoking history, comorbid diseases, and symptoms were recorded from the patients’ files. Subjects earning minimum wage (monthly income approximately less than 355 U.S. dollar) were defined as low income. BCG vaccination history was determined based on subjects’ self-declaration together with observation of vaccine scar by consultant pulmonologist.