Ageing, sex, obesity, smoking and COVID-19 - truths, myths and speculations.

In early December 2019, in the city of Wuhan in Hubei Province, China, the first infections by a novel coronavirus were reported. Since then, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been spreading to other cities and countries becoming the global emerging epidemiological issue and quickly reaching the status of a pandemic. Multiple risk factors of disease severity and mortality have been identified so far. These include old age, male sex, smoking, and obesity. This concise narrative review highlights the important role of these factors in the pathobiology and clinical landscape of Coronavirus Disease 2019 (COVID-19). We especially focused on their significant role in disease severity and mortality. However, in spite of intensive research, most of the presented pieces of evidence are weak and need further verification.