Background: A pandemic has been declared by the World Health Organization (WHO) for Corona Virus Disease of 2019 (COVID-19) on March 11, 2020. It is known that smoking inhibits pulmonary immunity and is a risk factor for contracting other infectious diseases. SARS-CoV2 is transmitted to humans by the angiotensin-converting enzyme-2 (ACE2) receptor.
Objectives: This study aimed to determine whether there were any differences in serum levels of ACE2 and COVID-19 patients between non-smokers and smokers, as well as to investigate the relationship between the level of ACE2 and the severity of the disease.
Methods: This case-control analytical study included 50 COVID-19 patients (25 patients were smokers and 25 patients were non-smokers) compared to 25 healthy control subjects. Quantitative detection of ACE2 serum levels was performed using the Enzyme-Linked Immunosorbent Assay method.
Results: The ACE2 serum level was statistically significantly higher in COVID-19-positive patients compared to the control group (p-value <0.001). ACE2 serum level could be used for the diagnosis of COVID-19 disease with a cut-off value (2.91). Among COVID-19-positive subjects, gender, smoking history, and disease severity were statistically insignificant in relation to ACE2 serum level. Different disease severity groups showed no statistically significant difference in the level of ACE2 between smokers and non-smokers.
Conclusion: This study revealed that the ACE2 serum level was higher in COVID-19 positive compared to the control group and could be used for diagnosis of COVID-19-positive cases. Meanwhile, it showed that smoking has no statistically significant effect on the levels of ACE2 in COVID-19-positive.