Smoking, vaping, and comorbidities associated with adverse COVID-19 outcomes

The coronavirus disease 2019 (COVID-19) pandemic has highlighted the critical role of individual factors, such as pre-existing comorbidities and risk behaviors, in the clinical progression of patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This article reviews current evidence on the impact of smoking, vaping, and various comorbidities on adverse outcomes associated with the infection. The ACE2 (angiotensin-converting enzyme 2) receptor and its overexpression in smokers may facilitate viral entry and worsen clinical outcomes. The shared pathophysiological mechanisms between nicotine exposure and COVID-19 progression are analyzed, including oxidative stress, immune dysfunction, and systemic inflammation. Common comorbidities such as hypertension, diabetes mellitus, chronic obstructive pulmonary disease (COPD), cardiovascular disease, chronic kidney disease, obesity, and neurovascular conditions are associated with an increased risk of hospitalization, admission to intensive care units, post-COVID-19 syndrome, and mortality and may also be related to persistent symptoms after the acute phase. The coexistence of comorbidities and exposure to nicotine-containing products represents a modifiable risk factor that warrants urgent attention. Strengthening prevention strategies, clinical monitoring, and tobacco cessation promotion are recommended as key measures to reduce disease burden among vulnerable populations.