Susceptibility of SARS-CoV-2 COVID-19 Infection among Smokers/Tobacco Users Upregulating the Expression of Angiotensin-Converting Enzyme-2 (ACE2)

Smoking is one of the major causes of mortality worldwide with a number of 8 million reported deaths each year. Smokers are more prone to viral and bacterial respiratory infections like chronic obstructive pulmonary disease (COPD) resulting in acute respiratory failure and reported to have higher mortality rates in the previous outbreak of Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Smoking was found to have a statistically significant relationship with the severity of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) outcomes among patients, including ICU admission, ventilator use, and higher mortality rates. The higher expression of the angiotensin-converting enzyme-2 (ACE2) receptor, a novel site of SARS-CoV-2 adhesion that causes COVID-19 infection in humans, among smokers further supported this link and placed them in the zone of vulnerability for SARS-CoV-2 infection.