A systematic review of studies on COVID-19 and smoking was conducted to evaluate the association between smoking and disease outcomes. The review included five studies published between 2019 and 2020, all conducted in China. The studies examined the smoking status of patients with COVID-19 and its relationship to disease severity, ICU admission, mechanical ventilation, and mortality. The findings suggest that smokers are more likely to experience severe symptoms, require ICU admission, or die from COVID-19 compared to non-smokers. For example, in the largest study, 16.9% of severe cases were current smokers, compared to 11.8% in non-severe cases. Additionally, smokers were 1.4 times more likely to have severe symptoms and 2.4 times more likely to require ICU admission, mechanical ventilation, or die. In another study, smokers were 2.23 times more likely to be severe cases, although this was not statistically significant. Another study found that smokers were more likely to be admitted to ICU, but the sample size was small. Despite these findings, the studies did not adjust for other potential factors that could influence disease progression. The authors concluded that while further research is needed, the available evidence suggests that smoking is associated with worse outcomes in COVID-19 patients. The review highlights the need for further investigation into the relationship between smoking and COVID-19, given the limited data available.A systematic review of studies on COVID-19 and smoking was conducted to evaluate the association between smoking and disease outcomes. The review included five studies published between 2019 and 2020, all conducted in China. The studies examined the smoking status of patients with COVID-19 and its relationship to disease severity, ICU admission, mechanical ventilation, and mortality. The findings suggest that smokers are more likely to experience severe symptoms, require ICU admission, or die from COVID-19 compared to non-smokers. For example, in the largest study, 16.9% of severe cases were current smokers, compared to 11.8% in non-severe cases. Additionally, smokers were 1.4 times more likely to have severe symptoms and 2.4 times more likely to require ICU admission, mechanical ventilation, or die. In another study, smokers were 2.23 times more likely to be severe cases, although this was not statistically significant. Another study found that smokers were more likely to be admitted to ICU, but the sample size was small. Despite these findings, the studies did not adjust for other potential factors that could influence disease progression. The authors concluded that while further research is needed, the available evidence suggests that smoking is associated with worse outcomes in COVID-19 patients. The review highlights the need for further investigation into the relationship between smoking and COVID-19, given the limited data available.