Introduction
Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus, the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) (Lai et al., 2020). An outbreak of COVID-19 has spread worldwide. As of June 3, 2020, SARS-CoV-2 has caused 6.35 million infections and more than 380 thousand deaths in the world, according to the World Health Organization.
Mild symptoms associated with COVID-19 are mostly fever, tiredness, and dry cough. Symptoms remain mild throughout infection in the majority of patients. However, mild cases can develop into severe cases of viral infections in the patients’ respiratory tracts become worse. Severe cases will have most likely developed pneumonia, acute respiratory distress syndrome, respiratory failure, shock, and other organ failures or risk of death (Wang et al., 2020; Wang et al., 2020; Zhou et al., 2020). The case fatality rate (CFR) is persistently increasing, and it is urgent to evaluate risk factors associated with severe cases as the pandemic evolves. Earlier intensive surveillance and treatment can then be performed to decrease the CFR.