International Difference of Tobacco Related COVID-19 Severity

This study aimed to analyze the correlation between smoking and coronavirus disease 2019 (COVID-19) severity by region and gross domestic product (GDP). The regions were categorized by continent and GDP rankings. Studies conducted be-tween June 3, 2020 and March 27, 2023 were searched to compare the severity of COVID-19 between smokers and non-smokers according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Compared with never-smokers, the smokers’ COVID-19 severity scores were 1.48 (confidence interval [CI]: 1.25-1.75) in Asia, 1.24 (CI: 1.05-1.46) in the Middle East, 1.32 (1.21-1.45) in Europe, 1.39 (1.30-1.49) in North America, 1.69 (1.22-2.34) in South America, and 2.87 (1.82-4.53) in Africa. By GDP, the smokers’ COVID-19 severity scores were higher than those of never-smokers: 1.42 (1.32-1.53) in high-GDP countries, 1.33 (1.25-1.41) in middle-GDP countries (11th-50th), and 1.53 (0.85-2.76) in low-GDP countries. The COVID-19 severity in smokers was significantly higher in low-GDP countries than in high-and middle-income countries. The high COVID-19 death rate among smokers in the African continent and low-GDP countries is thought to stem from the lack of medical management systems compared with other countries. In addition to medical treatment, environmental or socioeconomic factors can increase the severity.