“…Importantly, Muralidharan et al. studied the acute impact of short exposure to cigarette smoke extract and/or alcohol on SARS-CoV-2 infection of ciliated human bronchial epithelial cells of healthy subjects [19] , and found that viral titers were only increased in cells treated with both compounds but not with cigarette smoke extract or alcohol alone, thus emphasizing that cigarette smoke may only play a subsidiary role in the pathogenesis of COVID-19. Accordingly, the biological evidence that cigarette smoke alone would enhance the risk of infection and/or unfavorable disease progression remains weak, at best.…”