By Dr Ron Brown – Opinion Editorial
Why do some cigarette smokers have lower odds of testing positive for SARS-CoV-2 infections compared to non-smokers, while other smokers have greater odds of testing positive than non-smokers? These contradictory observations, a smoker’s paradox, imply that smoking in some people can protect against COVID-19 infection, even after ruling out confounding factors. But what is the explanation? Some theories claim there are therapeutic effects from nicotine and nitric oxide, but no theories have been found to explain the smoker’s paradox. Now, a new grounded theory (grounded in scientific evidence) has been published in a peer-reviewed journal, authored by yours truly: SARS-CoV-2 and Smoker’s Paradox: Mediation by Ciliary Beat Frequency and Mucociliary Clearance? Subscribe to the Trialsitenews “SARS-CoV-2” ChannelNo spam – we promise
This new theory explains how a high or low level of exposure to tobacco smoke can either upregulate or downregulate two bio-mechanisms within the innate immune system that normally protect against viral infection: ciliary beat frequency and mucociliary clearance.
Cilia and Mucociliary Clearance
Along the lining of the respiratory tract extending from the nose to the lungs, tiny finger-like projections known as cilia beat rapidly to help propel waste and inhaled foreign substances out of the body. The process of exhaling this material through the nose is known as mucociliary clearance.
Transient or light smoking can stimulate cilia to beat with a higher frequency than normal, thereby increasing mucociliary clearance and reducing odds of SARS-CoV-2 infection.
On the other hand, heavy or extended smoking can have a damaging effect on the cilia, reducing beating frequency that lowers mucociliary clearance and increases odds of SARS-CoV-2 infection.
Importantly, a negative test for SARS-CoV-2 infection associated with light smoking doesn’t mean that light smoking is risk free from severe COVID-19 symptoms and serious comorbid conditions like heart disease and stroke.