Introduction:
Novel Coronavirus disease (COVID-19) is a new infectious agent of the
respiratory tract characterized by a severe acute respiratory syndrome
(SARS). SARS-CoV-2 started in Wuhan, China in December 2019 and quickly
evolved into a rapidly spreading pandemic1. Because of
its high infectivity and mortality, it is a serious public health
threat2.
Although most patients are asymptomatic or have mild symptoms and a good
prognosis, COVID-19 can progress to more severe illnesses, including
pneumonia, acute respiratory distress syndrome, multiple organ failure,
or even death3,4. The aim of successful treatment is
reduction of complications and mortality. Basic disease treatment is
also needed to prevent secondary infection.
For this disease, there are limited data with regard to the clinical
characteristics of the patients and prognostic
factors5. Chronic diseases and old age have been
assumed to be associated with adverse disease prognosis. Little
attention has been given to the role of smoking in the transmission of
SARS-CoV2. Smokers contract more respiratory infections including colds
(commonly rhinoviruses), than non-smokers. Smokers also develop
influenza twice as often and show increased rates of bacterial pneumonia
and tuberculosis. The damage caused to the lungs by smoking makes these
patients more susceptible to pulmonary infections, both bacterial and
viral6.
There are two opposing opinions about the effect of smoking on
COVID-19’s severity. It has recently been reported that ACE2 gene
expression, which is known to be a cellular entry gateway for
SARS-CoV-2, is higher in smokers. This expression is also the
upregulation associated with smoking, this suggests that smoking
contributes to a higher number of viral receptors and may support the
findings of the recent case series research7,8.
However, the second opinion is that smoking prevents downregulation of
angiotensin-converting enzyme 2 (ACE2) and that this downregulation is
harmful due to uncontrolled ACE2 and angiotensin II
activity9. It has been observed that decreased ACE2
availability contributes to lung injury and increases the chance of
development of acute respiratory distress syndrome
(ARDS)9.
Therefore, it is very important to find the related factors of disease
severity in clinical practice. In this study, we compared the clinic and
laboratory findings and computed tomography (CT) features of 223
ordinary COVID-19 cases.